I'm riding STP for first time this year, too. I put together a 'team' (and I use this term quite loosely) by talking other first timers into riding with me.
I see plenty of posts on Cascade's STP/Events message board for more experienced riders seeking teams, and teams seeking riders. If you don't find others here, I'd try there. http://www.cascade.org/Community/Message_Boards.cfm
Are you aiming for 1 day or two?
Where do you live/train?