In the admin panel you will find the GridShow menu. Here, you can add new tiles to display to your users. You can set as many tiles as you want but the add-on will display only the first 12 tiles.
Users must have the View tiles permission set to view the tiles in homepage (default enabled). Admins must have the Manage GridShow tiles permission set to view the GridShow menu in the admin panel.
From Appearence > Style properties > GridShow Widget you can modify the style of the addon.