First mount the dvd:

mkdir /mnt/cdrom; mount -o loop /dev/cdrom /mnt/cdrom

Add the repository by going to the /etc/yum.repos.d directory and create a file. The name doesn't matter that much as long as it ends on .repo:

[root@redhatbox yum.repos.d]# vi dvd.repo
[dvd]
baseurl=file:///mnt/cdrom/Server
enabled=1
gpgcheck=0

Note: If you receive this error:

warning: rpmts_HdrFromFdno: Header V3 RSA/SHA256 Signature, key ID fd431d51: NOKEY
Public key for xorg-x11-drv-intel-2.16.0-1.el6.x86_64.rpm is not installed

You forgot to add the line “gpgcheck=0” in the .repo file.

yum grouplist
yum groupinstall "X Window System" "GNOME Desktop Environment"
yum groupinstall "Development Tools"

http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Installation_Guide/sn-switching-to-gui-login.html