modify pwd:

passwd

add user

useradd user1

passwd user1

groups

groupadd     

install GUI (version centos 6.2)

# yum -y groupinstall "Desktop" "Desktop Platform" "X Window System" "Fonts"

 http://www.idevelopment.info/data/Unix/Linux/LINUX_AddGNOMEToCentOSMinimalInstall.shtml

startx

# yum -y groupinstall "Desktop" "Desktop Platform" "X Window System" "Fonts"

centos