What should I do, please help?

She already knows, Im sure. When you like someone, whoever they are.. including your best friend they get a flow from you. Its a natural thing that happens when youre attracted to someone, you just pick it up. As far as being vocal about it, I think it will be good. Try not to make it awkward. Just explain to her exactly how you feel. That you never want it to be weird if she doesn't feel the same way... but that you cannot help but to be curious and just admire her. Good luck. If she does reject you... just get over it. I know it's hard, but there are PLENTY of fish in the sea.