the actual game started in the locked "game thread", and is continued in the threads that are stickied. none of the player's characters have run into each other yet, thus each character has their own storyline-thread. thus there are no "needed" classes. if you read through the entire "campaign announcement and parameters" thread (the one you accidentally posted in first) you will know the rules for this game.
i suggest that you read all the threads and get to know what is going on. then you can discuss with the players what is going on, and thereby get to know them a bit, and more importantly, them to get to know you, before you seek to join.