Shy people: How did you get over yourself enough to get a guy/girl?

I'm a junior in high school, and I've never had a boyfriend or gone out on a date...I've never even danced with someone at homecoming! I feel like I'm missing out, and since its summer, I really want a boyfriend, or at least a fling! I'm just way too shy it talk to anyone. I know I'm not ugly, but when I try to talk to a guy, I stop because I feel like they'll laugh at me. I'll even avoid cute guys working at the check-out of the grocery store! Please help me. Thanks! :)