Ok just get somewhere when theres just the two of you for your first time if your gonna get embarassed infront of people. Stare at her and move is slowely, you can gage her reaction and work out whether to go for it or not. You will soon get confident mate.
Dude you neeeeever get with a girl your mate is trying to get with thats just harsh, unless your having a competion on who can pull her :p
You just never go behind your friends like that.