Agree with everyone else - just relax and enjoy it, no-one else will care (they mostly won't even be able to see you!).

You can either play it cool, or just say straight up the the crew that this is a first time and a treat for you and you want to make the most of it - and ask what they would suggest; unless you've got a hopelessly new or tired crew, they'll see you right. But don't ever be afraid to ask for something if you want it.