You can create a private group or public group. All members must create a free account and log in to use the Groups
For a public group, a manager creates a group, and checks “open” membership requests on the form. Any user can request to join a public group, and memberships are accepted immediately. To join a public group, there will be a "Join" link on the left side at the top of the menu.
The easiest way to create a private group is to select "moderated" membership requests and "list in groups directory." In the description or welcome message, type that it is a private group.
To join a private group, members find their group from the list. After selecting it, there will be a "Request Membership" link on the left side at the top of the menu. The manager will then need to approve the membership.
A manager can also add members. On the group’s page, click on “# members” on the left menu. There will be an “Add members” tab. On that tab, a manager can add members if usernames are known.
If a group decides to change a manager, contact firstname.lastname@example.org to make the change.