OnMouseOver Help PLS!

Hi! i need some help. I am creating a website for a house and In the pictures page I have 10 pictures X 10 Pictures. I created buttons for each picture. On the MouseOver state I want the picture to be viewed at 500X500 with a transperancy so u can see the other buttons behind the picture. for some reason when i do so the picture is displayed behind all the other picture buttons. Does anyone know if there is a way around that?? I also tried creating a pop up for the picture but for some reason I cant get it to work. can someone pls pls pls help me try to figure this out i have looked everywhere for tutorials and cant seem to find anything on that topic.
THnx U guys for the help!
Daniel