Asking a girl out?

There is this girl that I really like and inf February one of her friends asked me if I liked her and she said she liked me too. Then a few weeks ago, a bunch of her friends kept asking if I like her and I said yeah but they didnt tell me if she liked me. Her b-day is coming up and I wanted to buy her a gift or something. But I wanna be sure. So if I ask one of her friends if she likes me, how should I ask?