well first he has to figure out how to "log in" to the router....has he figured that out yet?
usually it is spelled out in the manual or website
usually you go to internet explorer and type in 192.168.1.1 and then you have to know the password etc....which is also listed on the website.....
once you sign in to the router you should either look for "port forwarding" or "advanced" or something like that......I think if you can sign in to the router you will then be able to just look around and find port forwarding no problem
JP