Re: i'm new
Welcome to RPOL!
Whether or not you can use your pre-made characters will depend on the games you want to play in.
Go to the Wanted - Players forum, find a game that's accepting new players that looks interesting to you, and then read the threads the GM has put up for people who want to play in the game (usually something like "Character Creation", "Request to Join", or even just "RTJs"). If you like the look of the game, click the Request to Join link in the upper or lower right of the page.
I hope you find something you like.