Applying a theme to the entire public website

Applying a theme to the entire website is a generic method for applying a theme. If after that you apply a theme to a page or a template, this theme replaces the one applied to the entire website.

Go to Sitefinity’s backend (http://<yoursite>/sitefinity)
In the main menu, click Administration » Settings.
The Basic Settings page appears.
To open all setting, click Advanced.
The Settings page appears.
In the left menu click Appearance.
In DefaultFrontendTheme field, enter the name of the theme.
You must have registered the theme.
This theme is applied to all templates that do not have an explicitly applied theme.