Creating Minimap for Chaos Mode Maps?

[C̶a̶m̶p̶e̶r☻]

I'm working on my first map which is for the Chaos mode. I've created it in ZoneBuilder, played it, and now Im ready to create my minimap for it. Although I'm not sure how I would create & save it into my wad. I also have Slade & Gimp installed as well if I need to use that.

UPDATE: I have added the minimap but it seems to be incorrect lol