Incidentally, I felt like a dick the first time I decided to get my brows waxed. I thought they'd all be laughing at me because i had no idea how to ask for what I wanted.
Turns out they weren't, but our minds are not very kind to us at times. give it a good slap and get on with it.
eta: if that's part of your problem, I suggest finding a picture of how you want your brows to look and then just give it to the girl and tell her that's what you want.