How do i ask a girl out?

Hey! So I'm 17 and I have never dated.. (wierd, huh?) Well, I have met this amazing girl and we have been "talking" for the past 5/6 months. I have told her that I like her, and she has done likewise.. Sooo.. I really want to take it another step now.. but how..?? I know this may be crazy to some people, but I don't know how to ask a girl out... lol.. I guess it's not really how, but more like what to say. I mean, I couldd say something like, "Will you be my girlfriend?", but that sounds so... I dunno... wrong..? lame..? unoriginal..? I guess I could say "Will you let me get to know you on a deeper level?", but that just sounds like... wierd or something.. So what do I sayy? ...and I guess I need help on how to say it as well, like setting-wise.. I was just planning to do it like in the middle of the school football game, like take her out to my car as just ask..? I duno.. that sounds like it's not good enough.. like not movie-quality stuff.. or is it just never like that..? Girls: would you be satisfied with someone asking you out at a football game? or would that just be like a major turnoff?? Should I like have a rose? or some jewelry or something? And are you supposed to kiss after you ask her out.. I mean, I've seriously only seen this stuff in movies... haha.. I really need some help.. and fast.. thanks!!