How can I gain more confidence?

How can I be more confident? I mean a lot of people like me, like today at graduation practice I had one of the bigger applause's, so people must think I'm pretty cool...but like I always walk with my back hunched over, and stand with this slouch, every day I always wear a hoodie, because I don't have a whole lot of confidence. I'm not big or anything, I just don't have ANY confidence...