How do I ask out a girl via facebook?

I just read a post from one of my facebook friends. She posted one of those "rent me for valentine's day" pictures and captioned it "Because the struggle is real! Lol!" So obviously she's single. I'm single. Neither of us really have anything to lose. My only difficulty is actually asking her out. It's hard to ask out girls nowadays, because if you're upfront with women, they say "What a creeper," but obviously if I do nothing, nothing will happen. We don't even really know each other that well either. We only know each other through a mutual friend, and I don't want to make things awkward between us if we end up seeing each other more often in the future. So it kind of puts me in a weird situation. It really isn't necessary that I ask her out either, because it's not like I'm totally infatuated with her. If she dates someone else, it's not like I'll be heartbroken. She's just kind of cute, and we just so happen to be in the same boat as far as being single for Valentine's day. So should I take a chance or not even bother? If I should take a chance, what should I say? I don't want her to think I'm desperate, and I always over think these things. I just want the perfect way to ask her out so that if she says yes, that's awesome, but if she says no, it'll be cool and there won't be any awkwardness in the air.