Absolutely. I'm now a junior in college. When I was a sophomore in high school, I participated in my high school's FIRST team, and had a fantastic time. It was stressful, and for a lot of it, I was pretty confused! I really wish now that I had worked harder to make time the following two years for the robotics team.
I was on the team, despite my lack of knowledge of robot construction or programming. I got to see the robot go from idea, to construction, to competition, with all the steps in-between. There's always a way to lend a hand. Sometimes, you see something different than everyone else does; sometimes, you just need tot be there to see how the other people do it, so you can do it after them.
Once you've put in your time, you'll get to go to the FIRST competition, and have a blast. For my competition, I set myself up to be in charge of the batteries for the robot (a job of crucial importance, even if it's not glorious).
Your programming experience from AP Comp Sci will certainly help when you're trying to wrap your head around the programming concepts for the FIRST robot. (If you get good enough, your team can score big extra points in the autonomous round) Even though you've never built a robot before, you'll be in a room with people who may have, and their experience will help you understand the concepts much quicker than just learning it on your own.
Get in there, learn stuff, and have fun! And don't forget to ask questions.