[Edi]

I should add that nobody has done a comprehensive how-to walkthrough on modding. The modding.pdf has all the existing mod commands and documents what they do as well as how the syntax works for each different type of object (weapon, armor, monster, nation, magic site etc).

Even if there were some kind of walkthrough ala the game tutorial, modding and mapmaking is very much a process of learning by doing (and occasionally screwing up).