You can install a Desktop environment using yum groupinstall
. If you're running CentOS 6, you can try one of:
yum groupinstall Desktop
yum groupinstall "KDE Desktop"
yum groupinstall Xfce
to install the default GNOME Desktop, KDE or Xfce respectively. Use
to see a complete list of available groups. You may want to install the group "X Window System" prior to install the desktop manager, but I think it's required (and automatically selected) as a dependency. Good luck!
Edit: the command suggested by mesiol above is valid in CentOS 5, whereas the GNOME group in CentOS 6 is simply named "Desktop". Good to notice, anyway.