To edit an existing user group, navigate to the User Groups tab of the User Manager (Users → User Manager → User Groups). Then
To create a new user group,
User groups play a central role in what a user can do and see on the site. Creating user groups is normally the first step in setting up the security system for your site.
User Groups control what actions a user can take on the site. Actions include things like creating a new article, changing options for a component, or logging in. The site administrator assigns permissions for various actions to each group. Permissions for actions can be assigned at different levels in the component hierarchy (Global Configuration, component options, categories, and articles). If a user does not have permission for a given action, the user can not perform that action.
User groups also control which objects a user can view on the site. Objects include categories, articles, modules, menu items, and others. When you create an access level, one or more user groups are assigned to it. Then, when you create an object (such as a menu item or module), the object is assigned an access level. If a user is a member of a group that is assigned to an access level, this user can view any object assigned to that access level. If not, then that user can not view that object.
In this screen, you can create a new user group or edit an existing user group.
At the top right you will see the toolbar:
The functions are: