Open up your terminal and install tigervnc via yum.
Type this command in your terminal:
yum -y install tigervnc tigervnc-server
Edit the VNC configuration file
vi /etc/sysconfig/vncservers
and append these lines:
VNCSERVERS="1:user"
VNCSERVERARGS[1]="-geometry 800x600 -depth 16"
Where VNCSERVERS= is for configuring the username.