The process of creating a duchy is not complex at all. All you do is select a lord and click a button. *poof* That lord become the duke of a new duchy. This is not complex or difficult, and it all explained already in the game, on the page where you do it.
The problem, I think, lays in your still making the assumption of "city = duchy", which is no longer true. Well, that and I think you assumed the process was complex, made a mistake, got flustered, and panicked. Slow down, take a deep breath, and read the instructions you already have.
But if you want to add some instructions to the wiki, then by all means do so. That's why it is there.
