Set a VNC Password
vncpasswd
Start the VNC Server
vncserver 

Remember number at the end:

New 'X' desktop is ww8-node1.ww.uni-erlangen.de:#
Create a Tunnel
ssh -nNT -L 5900:localhost:5900 [USERNAME]@ww8[CLIENT].ww.uni-erlangen.de
Connect to the VNC Server from your Client

Use the Remote Desktop Viewer

And connect to localhost:# . The number behind de double point is the important thing.

Log In