When you click on the Edit Groups button in the Mange Users & Groups window, you are taken to the Edit Groups window. Here you can add or edit a group name.
Click on the "+" button next to the empty row in the table.
Two empty text boxes will appear in a new row at the bottom of the list. In the first box, enter the name of the group.
In the next box, enter the Friendly Name of the group. The friendly name is the file name for the group.
Click on the green check mark to save the group.
Click on the pencil icon next to the name of the group you want to edit.
The Group Name and Friendly Name become text boxes. Edit the Group Name and/or Friendly Name of the group.
Click on the green check mark to save the group, or the red "x" to cancel the group edit.