A programmer needed

Advertisement Script that rotates based on category page within Wordpress. The site is built on wordpress. The advertisement is in the sidebar. I need the advertisement to change based on what category page the visitor is on. There are 7 categories/pages so each page would display a separate advertisement. All ads are the same size 300x250. The script needs to be somewhere within the Wordpress theme that the client can access through the Editor and be able to add the image (either from the gallery) and the affiliate link (again either in the script or just calling on the image within the gallery which already allows you to add the custom URL (this would probably be the best option. I have many projects.I am looking for a long term [login to view URL] I like a programmer ,he will get more projects s just after this get done