There will be lots of different sounds noises, especially during taxi, takeoff, and landing. These are normal even though they sound strange. During flight you will probably hear almost a roar through the cabin - this is from the engines and is normal. I carry some foam rubber earplugs and use those when I'm trying to sleep.

You may feel occasional small shifts, shudders, bumps, etc while you are in flight. Again these are normal, think of these like hitting a small bump in the road while driving - same thing except the pilots are even more experienced at flying than you are at driving your car. You don't have problems with the small bumps/cracks in the road, right?

The airport transit can feel really strange especially for a new flyer. Flying from Canada, when you get to Toronto, you will have to go through US immigration/customs before you are allowed to go to your gate for your flight to LA. What airlines are you flying to/from Australia? At LAX, you may have to change terminals, depending on your airline. If you aren't certain where to go, ask an airline agent and they should be willing to direct you.

Tips for nervous first time flyer
 

I would watch YouTube videos on principles of flight and fear of flying videos. I find having science to support the unknown is a lot better than assuming you are sitting in some magic flying machine. Cockpit videos also help as you will see how structured and calm pilots are at all stages of flight.

Regarding noises, here are some of the ones of note:

1) Engine start: The air conditioning system will shut off and a few seconds later you will start to hear the engine begin to rotate. What is happening is a little turbine engine in the tail (APU) had been pumping air into the cabin and is now pumping air into the engine (simplified explanation). This spool up will get progrssively louder and then the engine will be rotating fast enough to be pulling enough air to introduce fuel. You will hear the light off as the fuel comes on and the engine comes alive.

After start: Depending on the aircraft you may hear some grinding noises. This is the hydraulics being pressurized. The air conditioning will come back on and the flaps will be extended which you will notice if sitting on the wing.

Takeoff: the engines will rev up slightly for a few seconds. The pilot is making sure they spun up properly. Then takeoff thrust is applied and you will be pressed into your seat. This is great fun!

Climb out: as soon as the plane has a positive climb the landing gear will come up. You will hear the retraction and might feel the doors closing. At about 1000 feet you might hear the engines spool down to climb power (not always). The plane will also climb at less of an angle. Depending on the plane'a weight and some the factors, the flaps will also be begin to be retracted.

Cruise: once at cruise the engines will spool down some more and the plane will level off. The engine sound will be less pronounced and you will hear more air flow and air conditioning noise. Expect on your long haul flights to periodically hear the engines spool up to that climb power and you will begin to climb. The aircraft will likely be to heavy to climb to its final cruise altitude in one shot and must burn off weight (as in fuel).

Decent: on decent the engines are brought back to idle and the plane pitches down. Periodically the plane will level off and the engines will spool up. The pilot might also raise the speed breaks to help slow down. These will raise from the wing and you will hear rough air and it might make minor bumpy turbulence. As you approach the airport the flaps will come back out (they will be more flap exposed on landing than takeoff) and landing gear will lower.

Landing: when the main gear touches the ground the spoilers (panels on top of wings used as air breaks) will raise again automatically. This removes the lift from the wings and puts the weight of the plane on the wheels to improve breaking and creates drag. You also might hear the engines spool way up. This is reverse thrust. A panel on the engine basically redirects the thirst forward to help slow the plane.

Welcome to the wonderful world of flying. I wonder how the Wright Brothers felt on their first flight?!

I'm flying Air Canada from Sudbury to Toronto and American Airline from Toronto to L.A and Quantas from L.A to Australia

Thanks everyone for the tips, I'm feeling a little less nervous right now :). I think takeoff is what I'm more nervous about once I'm in the air i should be fine

Tips for nervous first time flyer
 

I'm not a nervous flyer but found all the tips offered to the OP very interesting. Threads such as these make me glad to be part of FlyerTalk.

Wishing the OP safe travels.

You'll need to change terminals in Toronto (from 1 to 3). You'll also need to rescreen through security and submit to US Immigration and Customs, all at terminal 3.

Go here to see the connections guide. You may also want to ask the Air Canada baggage agents at arrivals in Toronto if your baggage will be sent directly to Terminal 3 for you. Make sure to ask in Toronto, as agents at your initial airport may not have precise information.

Thank you so much for the link :D.

Does anyone know if there a connecting guide like the one for Pearson for lax. I know that lax is a massive airport and I want to get from point A to point B with as little trouble as possible

Wish I could

When you land at LAX, you will arrive at Term 4 (AA's terminal). Qantas uses TBIT. You should not have to pick up your baggage at LAX and recheck it - so you will only need to worry about getting yourself over to TBIT.

In the evenings, there is a shuttle bus from Term 4 for passengers connecting to Qantas, leaves ever 30 minutes. It leaves from one of the Gates in Term 4. If you are able to use this shuttle, you won't have to reclear security at TBIT.

If for some reason you arrive and the shuttle is not running, then what you will need to do is exit the terminal, and then when you get outside, walk to the left on the sidewalk - takes 5 minutes at most - and you will be at TBIT. You will then need to reclear security.

Thank You so much

On long-hauls, I like to bring traditional books or magazines along with tablet/phone. At some point, I like to take a break from electronics.

Drink lots of water.

For the electronics, bring plenty of juice. If your device doesn't have a swappable battery, then bring one or two of those portable external battery packs. I have a 12000 mAh one that can juice a tablet and a phone at the same time. Cost $25 at Amazon.

I have a Samsung Galaxy S3, so I also have a few extra batteries in my backpack. ($3 knockoffs, not as good as the OEM battery but good enough.)

Your seat may or may not have a power source. If it does, it may or may not work. (About a 50-50 shot IME.)

Drink lots of water.

I'm an aisle guy because I like to be able to get up whenever I want. But some people are window people and that's okay too. When I am at the window, I tend to get up whenever Mr. Aisle gets up whether I think I need it or not. Figure it's good to move around on occasion, even if I don't use the toilet.

I don't bother with drugs. Well, other than wine... ;)

Turbulence has never really bothered me. People talk about it on FT, it happens once in a while, but I've thankfully never had to endure truly horrific turbulence. Most people haven't, and you probably won't.

Drink lots of water.

Pack light.

Be nice to the FA's. They'll be nice to you. (Most of them, anyway.)

Did I mention the water?

Xanax

Personally, I never use medications on flights.

In the unlikely event that something does happen I want my wits about me.

I may have 1 alcoholic drink... but that is the limit.

If you are going to be alone there will be no one else looking out for you so
all the more reason to keep your wits.

Pack light as possible and start assembling your items / packing list now.
Review each item critically considering "do I really need this?".

If you will be checking a bag keep in mind there is a chance it may end up
lost along the way... and you may only be reunited later or never. Bring a
carry-on with some basics to get you by for a day or two until you are
reunited or secure replacement items. Place information about your itinerary
and how to contact you in checked luggage.

No electronics or high-value items in checked luggage. Leave at home or
keep with you in carry-on.

Review each airline site for what is acceptable as carry-on / checked so
you don't end up fumbling somewhere along the way.

Review TSA site for what is acceptable in carry-on / checked luggage and
the procedures at the checkpoints. Consider going through with empty
pockets and only your ID (Passport) and boarding passes in hand.

Above all... enjoy the experience! It will be an adventure! :)

People have provided a lot of good practical advice, but sometimes when things get a little bumpy and I start feeling nervous, I will console myself with cold, hard facts.

Facts that might be helpful to the OP, like:

* QANTAS is one of the safest airlines in the world. They have been flying jet aircraft pretty much since they were invented, and they have never, ever, ever had so much as one accident-caused fatality on any of them. Just think about that...dozens if not hundreds of QANTAS jet flights a day for year after year, decade after decade and not a single, solitary crash victim. You have to like those odds.

* Air Canada is similarly safe. They fly in some of the harshest conditions anywhere, every single day... winter storms, ice, extreme heat, over the ocean, over mountains, you name it. And even still, it has literally been decades since they have had a fatality.

* From Time Magazine: "Statistical expert and MIT Professor Arnold Barnett told ABC News in 2011 the chance of being killed in an airplane disaster in the U.S. is 1 in 14 million — which means you could fly everyday for 38,000 years before dying in a fatal accident. Flying is also 23 times safer than driving, ABC News reports — about as dangerous as riding an elevator. "

The reality is that the hamburgers at the airport concession stands likely pose a far greater threat to your health and well-being than any amount of commercial flying.

And if this fails to provide comfort, I find some Crown Royal does the trick for me. :)

Bon voyage!