Hi, I'm 16 and I'm really interested in this girl from school. And I mean really interested. The thing is that we're not friends, and I've been struggling for a few months to start a conversation without coming off as a creepy guy. I finally managed it with the help of some common friends and we had a small talk today. I invited her to a party I'm throwing at my house tomorrow (30 persons or so), she agreed. I know I will be able to speak almost all night with her if I want to, but I don't know how to escalate. The worst thing is that she knows I'm interested in her, but she doesn't seem to feel the same (I'm not exactly beautiful but I think I could win her if I'm able to speak to her for such a long time). So, taking in count that I'm approaching as a friend, how do I escalate with her without making it seem obvious?

(Sorry for my bad english)