More listening, more questions. The key to having a good conversation is finding things the other person is interested in that you would like to know about. At 16, I know for a fact that I was in your exact same boat (going to an all-male high school didn’t help).
The hard part is figuring out if the other person is interested as well. At your age, odds are good that she’s in a similar position as you (a little socially awkward), so that’s a tough read. Just being aware of all of that is a big step towards bridging the gap. Self-awareness goes a long, long way, and will be the key to being socially confident.