Hi w91754,

I take it by your reply that you are not running PHP-Nuke, but you are running phpBB. In that case:

1. Upload the theme to /templates/
2. Go to phpBB admin.
2.1 Go to the main category General Admin
2.2 Go to the sub category Configuration
2.3 Go down to Default Style and select your theme from the drop down box.
3. Click Submit