Does anyone know of any tutorial to edit mortal kombat sprites?

Hi everyone, I know I'm not very active around here but I wanted to ask you, does anyone know of any tutorial to edit mortal kombat sprites since they are very different sprites from capcom and snk and I don't understand how to make shading or armor in these sprites they already have many colors if someone knows how they could explain or give me a tutorial, thanks

I m use gimp to improve images

Or to have a simply work in character you can work in fighter factory