DMZ by Luci @ LibreCMC

I have set up a Freedombox server (on a BeagleBoneBlack) and I am now trying to figure out how to connect it to the internet.

I have understood that the best solution is to setup a DMZ (de-militarized zone) in my router. There are several manuals and opinions on how to do that, but I don't have the knowledge to determine which ones are reliable.

Can someone help point me to a trustworthy manual?

My router is a Netgear WNDR3800 on which I have installed LibreCMC which uses the Luci interface.