Admin Area Template Files
From WHMCS Documentation
The main parts of the administration area are customisable in the same way as the client area. Below is a list of templates and what they correspond to:
- header.tpl - the header common to all pages
 - sidebar.tpl - the sidebar containing section links and stats
 - footer.tpl - the footer shown on all pages
 - homepage.tpl - the administration dashboard/overview shown immediately after login
 - clientssummary.tpl - the clients overview page
 - viewticket.tpl - the admin view & response ticket page
 - style.css - the CSS file defining the colors and appearence of all areas of the admin area
 
These files are all located in the admin/templates/themename directory, relative to your WHMCS installation's root.
See also Template Syntax