I guess that comes from watching too many movies when I was younger. You do need to get formal training. Never let a friend take you out diving to try it, or let them teach you. Seek professional help. It's not that expensive, and you will be safe that way.
Diving is easy, fun and safe when done properly.
Seek professional instruction. When you pass the training class, you will receive a certification card. Diver's call these a C-card. There are a few different certifying agencies. You should choose one that you find meets your needs.