Great, now you've asked a question and it looks like you've got spelling mastered. If you haven't read Christian's article do so. The basic premise is that you must know the transparancy colour. Will the blocks always move on just on plane or can they move on both? You need to identify each block of image and move it enmase. Otherwise you will not know if you're going left/right or up/down. Have a go and see where it's going wrong. Then come back and ask for some help at the next stage. Unfortunately, without knowing the method you are trying to employ it is rather difficult to help just yet. Now read Christian's article (he's v. clever) then have a go at a solution. If you get, come back and ask for some help where you are not sure. And have a Gin'n'Tonic, that helps as well. ;)
Panic, Chaos, Destruction. My work here is done.