The best way to learn is to participate. The basics are indeed quite basic, and can be picked up by looking at the game threads (set the forum to show older threads to see more of them). Simple summary: You need a scenario (set of starting conditions) rules (there is no set standard here; again, see existing or previous NESes for examples) and that's it. Gameplay goes according to the initiative of the participants.
dark ages nes STILL GOING! JOIN THIS!
a proposed constitution
Advanced hellenistic era nes
advanced hellenistic era nes part II
a bit of discussion on the theory of Nes playing
an example of the process of setting up an NES
another example of the process of setting up an nes
fall of rome nes
solar system nes
cold war nes
early united states nes