From this page you can create, edit, and delete local users and groups on the server. You can also change the members of each group. If the server is a member of a domain, you will not want to create any users on the server itself. The primary purpose of this page is to add one or more domain members to the local group.
You may also want to use domain user and group accounts to control access to resources on the server. You may also want to use domain management tools to manage domain users and domain groups.