well, i don't use normal abstract brushes, i just use rendering programs. downloading brushes is a big hassle, but anyway... on the part where the pic goes out of the banner, you need to get rid of the white majorly.
EDIT: the best way to do that is to crop the entire pic before putting it onto the banner at all, and make sure it is extremely well cropped before putting it on a transparent banner (or part of a banner), cause it's hard to cut after that.