How to create new type of terrain paint in the scenario editor

You see, I’m trying to turn the some ddt into terrain, where I can paint it using paint terrain, so I can use that to create map in the scenario editor. I got the ddt files ready and I think I’ve entered all the info and where to get the ddt file, but I can’t get it into scenario editor. So far, I’m trying to look into data and see what I can find, but I don’t know which xmb should I be looking into for reference. Which one is dealing with painting terrain within scenario editor? Because that is all I really need in order to make a very simple mod happen. Yeah I know, I’m a mod noob but I’m learning.

In age3 legacy, there’s a file called terrain.xml (or terrains.xml I’m not sure) in one of the Art bar. Most probably Art3.bar
I’ve never modded age3 DE apart from making a few AI scripts for my own use, so I can’t really help you, but I suggest you to search for terrain at least (in the resource manager).