Chances are you shouldn't use DMZ. DMZ opens every single port to the computer you'll point it to. Meaning that computer is very unsafe. I don't know what the ports are off of the top of my head but I know it is a set number.
To access router settings, in your browser go to
http://192.168.1.1 or
http://192.168.0.1. Those ones are the most common. Good luck