I can see why you're nervous, most of us started out RPing as nervous wrecks as well! But the fact is, you can't just sit by and watch, you've got to GET IN THERE! You have to converse with characters, get involved in Gm events, and sometimes you'll be yelled at and called a n00b, or a GodModder, but BAH! What are the other players going to do? Smack you via chat bubble? I think not. If you don't throw your character into the world, you're not going to be able to mold them. Get involved, be an ass, be a wuss, be whatever! It's YOUR character, and only yours! Like Phineas said, you have to decide whether or not you're an RPer, or sit on the fence until the game bores you to death.