First I know you are not alone in that kind of circumstance. I know of plenty of students in the past that probably have felt that same way.
I agree with the other posts above that we can't give you an exact solution without knowing some more of those details; however the best first step would be a combination of two things.
Finding a mentor on your team to pull aside and have a discussion with about everything you are feeling about this, the longer you wait to have that talk, well... its just that much longer til you look back and say to yourself wow... I wish I did this sooner. Mentors are there to help students develop in many ways, whether its learning how to use a drill, how to cad, write a grant, or giving them life advice. I have yet to go through a season without at least a handful of students asking various mentors about advice on choosing majors for college, help with school work, or even personal life advice. Point being: Mentors are there to help you, and if you ask one to take a little time to hear your concerns, most would go to pretty big lengths to help you get the most out of the program.
Second though is trying to self evaluate what you've been contributing in those hours (or attempting to since you say you haven't been allowed to do anything) and try to see the situation from a different point of view. Often in high school there are the social cliques that definitely play a part in who gets leadership roles or more involvement in projects. However there are often many kids who show up on some teams that, although they are there for a lot of hours, tend to be more disruptive than helpful. So just make sure you aren't the kid running through the halls throwing around game pieces like dodge balls, and rather are more so the student who shows up and asks "hey I don't have anything to work on, what can I do to help?". The latter tends to be the students who get the most out of FIRST and the mentors would rather give them more responsibility than the others.
Hopefully after a talk with a mentor or two on your team you'll be on your way to much more involvement on your team, and we wish you the best of luck!
