How to start a relationship with a friend?

So basically, I'm friends with this girl 2 years younger than me (I am a senior). Lately I have developed feelings for her but unfortunately I have no idea how to get closer to her.

First off I'd like to mention that she might already sense that I like her, but I do not know what her opinion is on it...

There is a dance coming up (Nov. 5) and I am going to ask her on Oct. 14 (or earlier if I want to avoid risking other people asking), but before that I want to get closer and hopefully in a way in which she can develop feelings for me too. To do that I know I have to get her thinking about me, what how? How do I move in and hint that I like her without being creepy/desperate/weird and obvious? We don't exactly talk everyday but she talks to me on AIM (but she is busy with HW and chores usually) and afterschool if I visit her at tennis practice.

I apologize for the bump but please respond =)

How about you ask her out on a date today? That way, you'll find out if she even likes you, and if she likes you she will probably go to the dance with you, but do it now. Go on a date once or twice a week, talk to her, and get to know her. Then you will get closer to her.

I know you're nervous, so was I when I was young. But man up and just do it. You have to start sometime. Better ask her out quick before someone else does.

I agree it's better you just go for it and ask her, that way even if she turns you down you'll atleast know where you stand.
Just be honest and say that you like her but don't overdo it, and be yourself.

So I should find a time when we're both alone right? I'm sure instant messaging is out of the question for this lol. So basically I shouldn't confess with the 'asking to the dance' but instead I should confess beforehand??