Recently had to set up port forwarding on a Yamaha NVR500 router in Japan (the router was in Japan, I was not!).
Google Translate was definitely my friend, as was http://alex.goodchilduk.com/2012/04/05/port-forwarding-on-a-yamaha-nvr500-for-ssh/ which pointed me in the right direction.
Find the Advanced options and Advanced Settings and Information – detailed setting of the basic connection.
You can either set basic port forwards, or as I have here used a DMZ host to forward everything to the Sonicwall behind it.
The button with Japanese characters on is the OK button. Router did reboot, or at least re-connect its internet connection, as I was kicked off, but it reconnected pretty quickly.