How do you add a dungeon to the game?

So I want to add extra dungeons to the game but idk how to open the game map to added them. I was wondering if someone could help me out with this please. Is the mod tools made not to let you open the map and change it?

There is a map decompiler on the forums somewhere that should help

Thank you I found the compliar and I’m going to try and get that working.