[Anonymous]

Any girl that is at all attractive and actually leaves the house will have been asked out and hit on a shit load of times. I know it seems like a big deal to you, but I assure you it is no big deal to her. She will not be impressed or offended or anything else like that. If she isn't interested she will give you her standard "no thanks" - whatever that may be. She won't lose any sleep over it, and there is a very likely chance she already knows you like her, and maybe even expects you to try and ask her out.
I know it seems like some huge move and it's easy to project that onto her feelings and think she will have some major reaction, but I promise you it is no big deal either way. Unless of course you do something creepy in asking her out like write her a 10 page love letter. (That happened to me a few times)
There is only one time in my life I was ever actually offended by someone trying to ask me out and that is because I hated the person in an intense and violent manner and were they not so socially inept they would have known that since it was obvious.
She will most likely take your asking her out as a compliment even if she isn't interested, and it shouldn't really cause weirdness between you as long as you don't make it weird and instead act casual about it all.