To add users or groups to your system, you can use the Users And Groups application located in Applications->System->Users and Groups.

To add a new user, click on Add user, fill-in the data fields, then click OK. To edit the properties of each user, click the Properties button located in the main window.

To add a new group, hit the Manage Groups button and click Add group. Choose a name for the new group and, if you want, change the value for the Group ID from the default. If you try to allocate a Group ID that is in use, the system will warn you.

You can add users to the newly created group by checking the user's name from the menu. Removing a user is as simple as adding one: select the group you want, hit Properties, and uncheck the user.

To remove a user or group from the system, select the user or group you want to delete and click Delete.