You can create a new group from the "Groups" section of the "Users" tab - see the whole process here. 

Note that only Admin and Manager users can create and manage other users in groups!

You can add a user to a new or existing group in two ways:

From the Groups page:

1. Log in to the Showcase web app and click Users at the top of the screen.
2. Select the ‘Groups’ tab.
   
   
3. Pick a group from the left sidebar.
   
   
   
   
   
4. Click 'Add User to Group' and select a user from the drop-down menu.
   
   Note that you can type a search term in this box and use the up and down arrow keys on your keyboard to navigate to different users on the list. You can also use the 'Enter' or 'Return' key to select that user from the list. This should allow you to add multiple users to the group in quick succession.
   
   
   
   
   
5. Voilà! The user has been added to the group!

From a user's page:

1. Log in to the Showcase web app and click Users at the top of the screen.
2. Search for the user you want to add to a group, or scroll the list to find them. Click their name.
3. Scroll down on the user details page - after the "Role" section is a section titled 'Groups'.
   
4. From here, you can select a group from the dropdown, and add the user there. You can even create a whole new group from this page if you need to!