1. In the “Groups” tab, click on a group.
2. Click on the "More" button towards the top-right of the screen. You'll see a drop-down list with options for “Manage Students” and “Manage Instructors”.
3. After selection one of those options, you should come to a page to add users to the group.
4. Check the box next to the appropriate users, and click “Add to Group” and then “Save Group” to save the changes.