Jinx,
Sure no problem. You can use either one graphic or two graphics to acheive a simple pop up. But you do have to create a page for the graphic to pop up into.
For a working example go to
http://www.apao.org/eigthann.shtml
The little stars are the links that pop up a window with only a graphic in it.
Now you could take the graphic and size it down via the img src tag for a thumbnail or creat a thumbnail. In this case I just used the stars.
Any questions give me a holler and I can elaborate more.