at first you should configure the VNC-Server software which is installed by default. Just go to menu and hack "remote" in. The right application should appear.
Now you have to allow the connection and make the other settings (which have to be set individually).
Now you go to your software manager and hack "VNC" in (of course on the computer you would like to view). You have to look for a VNC-viewer software. There are various different applications.
I use the Gtk VNC Viewer. Open the software and type the IP or hostname of your server in. Give your username and passoword (which you have configured in the server settings before) and click "add" or connect (different from application to application). Than make a double click on your added connection or just wait.
Now you should be connected to your vnc server host.