The extension should be installed from Manage.
Once the extension is enabled on its configuration page
Administration > Extensions > Design Spotlight
In the extension configuration an admin group can be configured to have access to the All Designs tab.
It makes changes to both the User and Admin site.
On Admin Site, the main left-hand menu, the top-most Activity section, contains the Design Spotlight menu-item which goes to the overview of all shared designs.
The most visible change is on the User Start page where it adds a Widget called Shared Designs. It displays two lists of thumbnails - recent and popular.
A new product meta field is created by the extension to allow admin users to prevent template from being shared.
