I'm trying to add a couple of promotional JPGs to a page to be picked up and displayed when the page is linked to on facebook. Trouble is, I don't want the images to actually appear on the page as they are essentially promoting the page and therefore not actually part of the page.

Has anybody managed to successfully do this? I've tried just FTPing the images onto the server in the same folder but facebook actually reads the HTML of the page. I've tried placing the images under a background image so they are effectively hidden but uploaded with the rest of the content but that doesn't seem to be working out either.