1. Upload the skin / template to the templates folder of your phpbb2 directory (eg. public_html/forums/templates), make sure you don't upload the zip archieve or a directory containing the directory where the template is in, the folder you need to upload usually contains a lot of .tpl files an images directory a .css file (or multiple) and if your template contains an admin re-skin an "admin" folder.
NOTE: If you use PHP-Nuke the directory where the forum skin will need to be uploaded is /modules/Forums/templates
2. Go to your forum and log into the administration panel (Log in to your own account and click "Go to Administration Panel" in the footer), at the "Styles Admin" part of the menu you click on "Add", if you have uploaded your template correctly you shoul be able to hit "install" behind the template name.
NOTE: If you use PHP-Nuke the forum administration can be found in the PHP-Nuke administration panel)
Optional: Go to "Configuration" under "General Admin" and set "Default Style" to the template you just installed, this will change the template guests and new users see to the new template. Also, if you "Override User Style" everyone will see the template.
