Advertising banners are created and activated by the site administrator, so for the non-admin Tiki site user, normally the only interaction is to view the banners being displayed and click on them if desired to visit the linked-to web site.
However, the "client" of each Tiki banner is selected from the list of registered site users. The client can view the banners assigned to him/her by accessing the banner stats page (tiki-list_banners.php).
The site admins should be contacted regarding any requests or comments about banner ads on the site.