Go to "Ext" at Zsite, you will see "Extensions" and "Theme". You can manage extensions here. There are three types of extensions, Installed, Deactivated and Available.

You can install Zsite extensions locally. Click "Get Extensions" at the upper right of the window. Zsite official extensions and third-party ones will show. You can install extensions with one click and it will automatically run and install. If the automatic installation is not working, download it to your machine first and then install it manually.

You can also view Zsite themes by going to "Ext"->"Themes" and check the theme details and shop it online.