Step one: Don't say female. Saying that makes you sound like you're massively out of touch with reality. Just say "woman". Even if you're both 15, call her a woman.
Step two: Talk to her like she's a person with thoughts and not just a pretty face. Ask how she's doing. Get to know her. If she blows you off, it sucks, but it's gonna happen eventually with a woman you're attracted to.
Step three: Go from there. Again, be prepared that she doesn't reciprocate your feelings. It hurts to get shot down, but (and I say this because this is the internet and I have to, not because I'm certain you're a loon) she doesn't owe you a thing. Power move if that happens is to keep talking to her as a coworker/friend unless she makes it clear she doesn't want to talk to you at all.
Side note: Where you work doesn't matter. People meet friends, lovers, acquaintances, spouses, and all the rest at work.