What should I do with Her?

So I have liked this girl for the whole school year and now it's the summer and I won't see her. She was a freshman and I was a junior in high school. We both had band cl together and have gotten to become good friends over the year. I think she liked me at the beginning of the year but then she moved on because I was too shy to do anything. I think I blew it! :[. We both talk on AIM and on facebook. We have been talking on AIM and I have been feeling hopeless with her. Sometimes she IM's first and then sometimes I do. I really do like her ALOT. Is there any way I could subtly hint that I like her on AIM...or tell if she likes me?