You can control where the classified photo(s) are displayed by changing the Page Format of your Classifieds content page, on the Pages > Edit Page.

You can customize the photo slideshow/gallery/display (animation, control buttons, loop, etc.) on the Photo Category page. First, create one: Admin Panel > Photos > Add Category. Then on the Admin Panel > Configure Site > Social Networking > Classifieds Config page set the "Default Photo Category" to this photo category.