if u've seen a vid on youtube that shows u how to do it i'l need to explain a little farther.

ONE theing the vids i saw didn't tell me was that u need a "floating" whammy bar to do this.

"floating" bars wah both ways dropping an raising the sound. Floyd Rose Tremello's are the brand of tailpiece/whammy that Satriani, Steve Vai, Dimebag, and more use.