Stealthy, for the Code to be shown you can put in whatever you like and it will replace $advert in any of your code, it can be images, text or javascript. Its up to you it doesn't matter what you have.
I have
Code:
<a href="http://www.site.com"><img src="http://www.site.com/banners.gif" alt="Website" /></a>
active, do what the instructions say in the text file within the zip. Make the code changes and then upload ads.php then run the sql query at the top to create the table.