There are 5 “reserved” groups that are automatically created based on a contact's activity:
Contacts can be part of multiple groups, and these groups cannot be deleted or edited.
You can create additional groups (ie: Board member, Volunteer, Major Donor, Offline Donor, etc) to help you segment your contacts further in your Community.
Step 1: Navigate to your Community and select "Create Group" in the group listing on the left.
Step 2: Write your group name and save.
Step 3: You can assign contacts to the group when you select the contact and add them to the contact card (shown in the sidebar).
You can also create a new group by typing in a unique group name on the contact card directly.
You can edit or delete a custom group at anytime.