I'll echo Ed's




but try to be helpful with some advice here.
OK, here goes JB. Let's try to keep this simple so you can get laid without too much dithering. The chick has the hots for you. Just talk to her, flirt with her, be friendly but don't be too nice to her. Have lunch with her alone and then go to a secluded place where you can look into her eyes and bullshit her about how you think she's really hot and how you'd love to take wine+dine her and spend a long romantic weekend in a penthouse suite with her where you can have breakfast in bed... Look for her reaction and then make your move to kiss her.
Very important: If you want to get laid, remember this: Do not talk to her about any relationship crap. Don't get all sappy and sentimental. Be decisive and don't always ask her what she wants. Just suggest something and explain how great it will be.
For example:
what do you want to do now? = bad
I know this great place we can watch the sunset from and drink this bottle of chianti I swiped from my dad's wine fridge = good
Don't let her know you have no experience and don't know what you're doing. Pretend you do this all the time. Don't worry, it should come naturally to you. I realize it can be somewhat intimidating but always remember that girls are just as (and usually more) horny and curious about sex at 17 than you are, so don't be afraid to make sudden moves. She wants it too and is waiting for your cue.
And btw, none of that inviting her friends crap. That can happen after you've nailed her but not before.
Now go get her and no dithering!