You may have been added to a group by your Instructor or ATLAS Organization Administrator. 

You can see the groups to which you belong from the dashboard. Open the dashboard and click on the group name from the Groups section. If you do not see a group listed, click on "Open My Groups" to see all your groups.

Your Instructor/Group Leader will save cases to your group and you can create notes about the case to share with your fellow group members and your Instructor/Group Leader.