i installed Red Hat enterprise linux server 6.4 on my pc.
Its entirely likely you selected server install, which doesn't install GUI; most serious servers don't bother (they don't have monitors attached when rack mounted).
Try going back to the cli & 'startx' cmd as recommended and post the msgs.
You could try installing the GUI (as root user)
yum install "Desktop Platform"
# see this cmd to list all pkg groups