If enabled from the main Administration Panel (see TikiAdminSettings ) you will see a link to Edit Templates in the Admin Menu. Click it and the Edit Templates screen will display a long list of templates. Essentially, they're just the TPL files in the templates directory and its sub-directories. Select a TPL file and its code will display.
The main TPL file that controls the overall look of your Tiki is listed as templates/tiki.tpl.
To edit it, you'll need to know about HTML, CSS and Smarty, the ornery template engine ( SmartyTplEditingDev ). Once you're finished, save the template and check the result by reloading a page on the site.
The Edit Templates feature can be used to make very nice changes or effects in your sites. For example, you can include a logo at the top of the page by editing the tiki.tpl template and you can change the logo on special occasions (as Google does).