Welcome to FT and the friendly QF forum, zebidos!

Time will fly on that flight (pun intended). You will be able to watch the latest movies, QF will feed you properly and there is always the open bar. So don't worry.
Have a look at the QF Meeting threads in this forum. Maybe someone flies on the same day as you can can guest you into a lounge at the airport.

Make sure you have your electronic travel authorization for the US before boarding the plane. Otherwise, the process is pretty straight forward in LA. You will be directed to immigration first where you will be fingerprinted and photographed. After that, you will wait for your bags before clearing customs.
My advice is that once you are off the plane, try to go quickly to immigration. Try to pass as many people as you can so reduce the queue at immigration.

Enjoy your first flight!