-Open Cubic Castles file location ( Local Disk>Program Files (x86)>Cubic Castles ) - these are for windows, idk when it comes to steam >.<
-go to DynaContent>Images
-check those images and edit them, should be png
-replace those previous images with the one u edited then open cc
Make sure to have a backup file before editing xD u might regret it lol
btw im not sure if this is still the file location since i havent played for quite some time
Well, since the Windows version doesn't still work, here's how to do it for Steam on Windows 10:
This PC
> Local Disk, usually C:
> Program Files (x86)
> Steam
> steamapps
> common
> Cubic Castles
> DynaContent
> images
Replace whatever images you want with your own textures, just be sure the name of the file stays the same :)