Where to begin

I suppose something that made me really happy after I was suicidal and depressed for about three years was getting myself busy with hobbies such as Track and Field, Stage and Tech design (building props and the set for plays)... and what really boosted my confidence was going to a convention where people had the same hobbies as I did and no one cared what other people thought of their actions or how they looked. I put myself on staff for that event and found people who wanted to talk to me, was very social and friendly, and had the same hobbies (it was an anime convention, if you were wondering).
I didn't have enough time to be depressed or worry about not making a good impression. I was working with people where communication was essential and we all had a common trait through the activity/hobby. It's easier to gain confidence when you have people you are comfortable with around.

Finding a hobby and finding what you love and are passionate about while sharing it with other people is something I usually recommend for people who don't have confidence in themselves. It really does work. You just have to be willing. (;