Add a user in ubuntu 10.04

[1] If you'd like to add new user, Do like follows.
lucid@ubuntu:~$ sudo adduser ubuntu # add a user "ubuntu"
Adding user `ubuntu' ...
Adding new group `ubuntu' (1000) ...
Adding new user `ubuntu' (1000) with group `ubuntu' ...
Creating home directory `/home/ubuntu' ...
Copying files from `/etc/skel' ...
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully
Changing the user information for ubuntu
Enter the new value, or press ENTER for the default
Full Name []:# if not needed, Enter with empty
Room Number []:
Work Phone []:
Home Phone []:
Other []:
Is the information correct? [Y/n] y
lucid@ubuntu:~$
[2] If you'd like to give a privileges to a new user, Do like follows.
lucid@ubuntu:~$ sudo vi /etc/group 


# near line 50: add in admin group
admin:x:111:lucid,ubuntu 


lucid@ubuntu:~$ su - ubuntu 
Password:
To run a command as administrator (user "root"), use "sudo <command>".
See "man sudo_root" for details.


ubuntu@ubuntu:~$ sudo reboot # try to execute
[sudo] password for ubuntu:# input own password
ubuntu@ubuntu:~$
Broadcast message from lucid@ubuntu
(/dev/pts/0) at 2:28 ...


The system is going down for reboot NOW!   # success