How do I ask a girl out that I met and kissed at a party?

[Hamo27]

I'm a 16 year old guy just so this is clear. I met this girl at a party, I kinda like her although I'm not sure how to ask her out. She isn't someone that I can see in person really. I already kissed her at the party and I got along with her pretty well.

We discussed going out to see a movie, but when I asked her if she wanted to see one she said she had too much homework. Should I ask again now that school is finished?

And its hard to tell how much she actually likes me, or if she likes me as a friend - because some people have made it plain to me that some people "hook-up" for no reason these days.

Anyone who could help me would be helpful!

As for extra details, she kept looking into my eyes the whole time i was talking, she was really nice, reacted well to my jokes, I talked to her for a good 30 mins, probably more. While I went to the toilet she sat down and was waiting for me, and later she asked me to come dance with her and gave me a hug when she left.

As for recently, I haven't talked to her much on text messages, and normally she doesn't say much on texts, only things like "haha" and "oh true" - she may just be different on her phone to in person I'm not sure. On two times I tried to talk to her on facebook she didn't reply, but a week later when i texted her she replied.
hopefully thats enough details to make a judgement about this.