I have to second Fullcrum here, just go out and start talking to random people as much as you can. Male or female either one, don't try to "hit on" them or anything just yet (unless you really want to), just get used to talking to people you don't know and being yourself! It sounds kind of simple, but for many it isn't so easy to do- I used to be really shy, so I know how it feels. So long as you don't have any set expectation, such as trying to get a date or make a new friend, you really don't have anything to fear from talking to others, and so it comes along much easier in the sense that you're just making friendly conversation as opposed to expecting any sort of result.
Confidence really comes from learning how you'll react to given situations, and how to control yourself in those situations, so IMO (and experience), the best way to do that is to just start forcing yourself to interact with others outside of your "comfort zone". I can give examples if you'd like, just let me know
