About port forwarding:
Enter the Basic setup of your Router using any browser. Just enter 192.168.1.1 (this is the default address), then the user name and password.
Enter applications and gaming
Here you can control the port forwarding:
Visit LINKSYS WRT54G port forwarding. Look for the application you are going to use port forwarding for - in your case search for VNC.
Follow the steps on the website.