The module contains all the code necessary to run a modules gallery for Orchard as seen on https://gallery.orchardproject.net
To setup a gallery:
It will create the necessary content types and taxonomies. You can then browse the gallery urls or add packages and versions.
The module works better when you use its custom theme which is on https://github.com/OrchardCMS/TheGalleryMachine. This theme is a child theme of https://github.com/OrchardCMS/TheBootstrapMachine so it will be required too.