Official TSA Website - Everything you need to know can start right here. Definitely check out the event lists for an overview of the possible topics you can compete in. *These lists do change some years, so check with a coach for any possible updates:
LEAP - TSA's leadership program stands for "Leadership. Education. Achievement. Personal Growth." Available to all TSA members, it is an opportunity to learn about leadership behaviors so they can grow into the best person they can be.
Official Junior Solar Sprint Website - A great starting point if you are interested in this event. It contains some useful information about supplies and ideas.