Use this wiki plugin, introduced in Tiki3, to add a banner onto a page.

Some sites like to hide banners from some types of users, for example to prevent forbidden clicks by staff. In some parts of TikiWiki, such as in Modules and the Look & Feel headers, the following can be used to make banners only visible to anonymous visitors.

{if (empty($group)) or ($group eq "Anonymous")}
{banner zone="name" target="_blank"}
{/if}

• Banners
• Banner User
• Banner Admin