Style Image Window

I was wondering if there is a way to add some simple design elements to the window that pops up when you click on an image thumbnail. As of right now, when I click on an image thumbnail, it pops up in a new window with the original photo aligned on the left and it has a white bg. I would like to center the photo and use a black bg. (Where would i put the following code: align=”middle” bgcolor=”#000000″)