Admin Area Template Files
From WHMCS Documentation
Certain parts of the administration area of WHMCS are customisable in the same way as the client area. This has been available since v3.6.1 but as of version 4.0.0 the following areas can be customised:
- The admin area header: "header.tpl"
- The admin area footer: "footer.tpl"
- The administration dashboard/homepage: homepage.tpl
- The left-hand statistics panel for all pages: "siderbar.tpl"
- The clients summary page: clientssummary.tpl
These files are all located in the admin/templates/themename directory, relative to your WHMCS installation's root, which also contains style.css and the images folder so you can customise the appearance and colors of your administration panel.
See also Template Syntax