How do you have the vncserver configured? The easiest way to get it going is to edit /etc/sysconfig/vncservers to tell it what VNC sessions you want available. Mine looks like
That gives me a vnc session on display 2 (port 5902) at 1024x768.
To get the service to start automatically, use chkconfig to set it to come on when you go into run levels 3-5, and use the service command to bring it up now.
I hope that points you in the right direction!