Note that this recipe is meant for Theme Packages which you get as a zip file. If you have a normal folder, use this recipe to install a theme-folder instead. 

Installing a Theme Package

To install a DNN theme on DNN 9, do the following:

1. Install the theme just like you would install any extension
2. Now apply it to specific pages or to the whole site
3. Note: if the home page still shows the old theme, it's probably because it's a bug in the default dnn-installation, which assigns a theme to the home page directly (so the site-default doesn't apply). In that case, also apply the theme to the home page specifically.
4. Remember: on multi-language solutions you must set the default theme on each language