How to port forward a Netgear router?

Hi I'm having trouble port forwarding a Netgear CG4500BD. I want to portforward 25565 for a minecraft server my my brother and I. I use Cox Cable And Internet. In my settings I can't add a custom service it just has Port Forwarding and Port Triggering separate not Port Forwarding/Port Triggering just to be clear.

"I can't add a custom service"

Why not? Are you getting an error when you try? If you can, be sure to update the firmware for that router, and then try your forwarding again.