First we need to open the Demo Install page by navigating to > Appearance > Demo Install. Now simple choose the WordPress theme demo you wish to use and click on the install button. Please see attached image below.
It takes 2-3 minutes on average for the installation to finish. In some rare cases, depending on your server specs, it can also take up to 10 minutes.
Do you already have a running website with content and you do not wish to install the dummy content?
Please read the following article on how to install one of the demos without the “dummy content”: