Help with mods (Sid Meier's Civilization 6)

Please help with mods, namely modding. I was going to create a mod for a nation, but there was a problem in the form of a lack of guides. I found it overseas, but not everything is explained there, but I would like to learn more. I want to create a nation (I know how to do this) and make my own ability for it, and not taken from another nation. I also want to replace great people with others and add my own units.
Okay, if you shit on the nation, then how to make great people or replace the old?