How to let a girl on Facebook know I'm interested in her?

[ZLD]

I recently became Facebook friends with a girl whom I knew like an acquaintance through a college class we had together. The semester is now over, but starting a couple of weeks before that, I've thought about asking her out or something.

Facebook messages/chat is currently the only way I can contact her, but with her apparently being busy quite often, she and I haven't had an actual chat yet. When we get a chance to talk through FB (or maybe some other means like text messages), how can I let her know that I'm interested in her without coming on too strong? Since we should probably get to know each other a bit as friends first, what could possibly direct the conversation toward that topic?

Our first online conversation may be several days away, or maybe it'll happen within a few hours of this question being submitted. Who knows. *shrug*
After we became FB friends, I sent a few messages about getting to know each other as more than former classmates and having a conversation sometime. But I don't know if I should send any more before she replies from her side of the chat window. I can see how online messaging on a semi-daily basis could become annoying, and of course, this could just be a matter of impatience on my part.

[Kathy]

You could send her a message that says, "I don't know you very well but I'd like to get to know you better. Would you like to get some lunch (or whatever)". Don't do it on her page, send it as a private message.

[Yusif]

Yeah just ask her out to a movie or something. Maybe a walk in the park if the weathers good