Just start with your trusted guys already in the list of your friends. It would show more confidence in you asking one to go out with you but don't do it desperately. If you don't happen to get one in time, just appear at the dance and they will be there. Remember to remain yourself and challenge them with dignity.
just talk to guys at lunch or if you are paired up for assignments also while you're waiting for your mom or dad to pick you up in the afternoon or meet them at extracurricular activities that you enjoy .