I'm not sure what to do... Any advice?

I just graduated 8th grade, and I'm on summer break right now. For our ceremony we had to sit in alternate alphabetical order, and I ended up next to this girl I hardly knew. It turned out she was pretty cool though, and we talked a lot while we were practicing the ceremony. On the last day we had an entire school year book signing, and while I was with my friends signing it turned out she was friends with a few of them. So then she's like "Hey can I sign my yearbook." I said ya, and she wrote her cell phone number in my yearbook. Sooo... I texted her one day and now we haven't gone a a day without talking at least an hour. I think I kinda like her, but were just friends right now. Oh and while we were walking out of graduation practice I hear her say to her friend, "Dave and I are like best friends now!" Any advice on what to do about taking our relationship further?