lol. k.
So you wait till she knocks of work or whatever each night for about a week.
Hang around outside make sure she sees you, then hide or run away.
Then after a week of nuturing her paranoia, start following her one day. Preferably at night, and preferably with a hood or something that conceals your face.
Now once she comes to a particularly lonely part of the suburb, pick up your pace, maybe make some grunting sounds.
If all goes well she'll do the same, and eventually break out in a run.
Here's where you need to corner her in a dark alley. Now when she starts screaming out for help or reaches for the mace, rip your hood off and ask her.
If all goes well you'll have a date for the prom or whatever its damn well called. If things go bad you may get maced and a restraining order.
Else just catch her before class and ask her matter of factly if she wants to come along with you.
Either way works... Generally.