The instructions below are not terribly detailed, but should get you moving in the right direction.
#################################################
## These first several can be run directly as root
## or via SUDO
## Make sure all of the packages are up to date
sudo yum -y update
## This provides extra packages not included in the base
sudo yum -y install epel-release
## This is optional, but is a sanity-saver
sudo yum -y install bash-completion
## This installs the XFCE desktop environment
sudo yum -y groups install Xfce
## This installs your VNC Server
sudo yum -y install tigervnc-server
## This puts the VNC server under management by systemd
sudo cp /lib/systemd/system/vncserver@.service /etc/systemd/system/vncserver@:1.service
#################################################
## This next one should be run from the user as
## whom you will log-in using VNC. This should
## NOT be root
##
## If the user is not able to issue commands as
## root using SUDO, you will need to manually edit
## the file /etc/systemd/system/vncserver@:1.service
## as root and put in that user's name instead
## This puts the VNC user's information into the startup file
sudo sed -i -e 's![<]USER[>]!'"${LOGNAME}"'!g' /etc/systemd/system/vncserver@:1.service
#################################################
## This next one should be run from the user as
## whom you will log-in using VNC. This should
## NOT be root
##
## Set the VNC password and configuration for VNC user
vncserver
#################################################
## These next ones can be run directly as root
## or via SUDO
## Make sure VNC Server starts at boot time
sudo systemctl enable vncserver@:1.service
## Make sure systemd has picked up the new configs
sudo systemctl daemon-reload
#################################################
## This next one is only needed if you are running
## FirewallD
## Allow VNC Server traffic through the firewall
#sudo firewall-cmd --permanent --zone=public --add-service vnc-server
At this point, you should be able to access your server via VNC (the connection address would be the server's IP, followed by a ":1", so if your server's IP address were 10.253.126.17, the connection address would be "10.253.126.17:1").
Note, you will likely need to configure XFCE to do anything useful, like start a window-manager (xfwm4) and a terminal (xterm) when you log in, but that's another story, for another time (and you can probably figure it out from http://docs.xfce.org/)
