How do I add my Advertisers banners to my directory website pages?

How and where can I place banners on the front and category pages of my directory. I saw other geocraft directories that already have some in similarity, I just don't know how to go about it. I need to offer this option to my advertisers and supporters. How can this be accomplished? Your help would be greatly appreciated.

Best Regards,
Gino
www.AdultEscortListings.com