How can I cure my SAD at home?

As a child (from kindergarten to middle school) I was picked on, teased, and bullied horribly. I'm not in High school and I CANNOT bring myself to even talk to anyone my family, friends, or myself doesn't know. I go to many high school rodeos that have dances and many other social gatherings alongside all the kids goofing around after ward. Anyway I'm begging to become very depressed because I see all of the other kids having a good time and laughing and I just wish I could be like them but I can't bring myself to. If I'm with my friends I'm usually ok and not to bad or if my brother has a friend over I can make myself talk, only then I come across loud and annoying because I'm so nervous I can't hardly control what I say. My family can't afford medical treatment not to mention therapy and they don't even know of my condition. They think I'm just really shy. I don't have many real friends although I have several people who are pretty nice to me. I was wondering if there is any way to cure my SAD at home? Thank you!