Similar to the user commands, there are commands for controlling groups as well. They are
The groupadd command allows you to add groups to the system from the command line. To do so, log in as the root user and enter the following command:
[root@insocoxygen /root]# groupadd groupname
where groupname is the name of the group you want to add to the system.
For example, to add the group www to your system, you would use the command:
[root@insocoxygen /root]# groupadd www
See the man page regarding groupadd for a full list of all the command-line options available.