To install a PHP-Nuke theme you need to do the following steps.
First of all you should unpack template package using instructions from Unzipping Template Package section.
There is will be a folder named XXXX (four digits number). This is the PHP-Nuke theme folder. Copy this folder to /nuke/html/theme where nuke is the folder to which PHP-Nuke is installed.
Next step is to select a theme from list of themes Your Account -> Themes.
If you want to use it as the default theme for your site, move to Administration->Preferences and set Default theme to the theme you bought. Notice that you must be a member of the administrators to change default theme.
Fig 6.3 Administration Panel
Fig 6.4 Change Default Theme
If your PHP-Nuke theme contains animated flash header you can customize it using instructions from the Table of Contents, Flash section.