HI jeney,
I’m not sure what you’re asking here exactly–what is it you are trying to customize, specifically? Are you talking about banner ads or classified ads? (Since we support AdSense in the classifieds, it’s not clear which you want to customize)
If you’re talking about customizing the basic layout of the ads, that’s handled in the Single Ad HTML and List Ad HTML templates. You find these under Classifieds->Settings, Ad/Listings tab. The documentation covers how to modify them: http://awpcp.com/documentation/#settings-ads
If you’re trying to change the style of the classifieds, that’s best handled through custom CSS. Here is an article about how to use custom CSS with AWPCP in a way that doesn’t get overwritten on upgrade of AWPCP: http://awpcp.com/forum/faq/how-to-use-custom-styles-with-awpcp/
If you meant something else, can you describe it in more detail?
