Theres this girl....?

So theres this girl, I started to like her about 6 moths ago, and i started to get close to her. I asked some friends that are close to her for her number, but nothing. Then one day i was at a party, and i get a text that said "Hey this is ______ and i was wondering why you asked Ashli for my number?" I started freaking out! I really like her alot. So i told her i liked her and she thinks im just kidding because i was so straight forward with her! SHe also said that i have to get to know her better. How do i get her to trust me and say yes if i ask her out?