Modding help - How do I modify the settlement pictures?

[SwiftUnity]

Hi I was wondering how I would go about modding the little settlement pictures that pop up when you click a county. For example the church icons, city icons, castle icons, and trade post icons. Also how would I change the province terrain pictures? Such as when you open the extended province menu and see if it's plains, mountains, farmland, etc. Any help would be appreciated!

Thanks