To add a usergroup, click
Usergroups > Add New Usergroup. To edit an existing group, click
Usergroups > Usergroup Manager > Edit Usergroup for the group you wish to edit. Both links will take you to a similar page:
This is part of the form to add a new usergroup. If you are editing a usergroup, the form will already be filled out for you.
The only difference between the add- and edit-pages is that, when adding a new group, you have the ability to create a usergroup based off of an existing usergroup:
If you use this option, all the fields will be populated with the values specified for the group you selected. Simply change whatever fields you wish to change and submit.
Most settings should be self explanatory. If you are unsure of an option, simply click the inline help icon for a further explanation.