Just tell you like her, straight out. That's how you'd win me anyway. Plus, what's the worst that could happen? You get turned down, slightly embarrassed, that's it.
Don't worry, I've been in this position twice. The first time I got turned down, and I was embarrassed at first but everything was fine after, but I didn't talk to him much.
Then the next person, ok, also turned me down. But we became like best mates, and we get along fantastically, he had bearly noticed me before I said anything.
Best of luck.
XXX