How in the world do you do that?
This is for MS Paint
Step 1: Turn the parts that you want to change into one color. This includes shading and everything. Resize your sprite to x4
Step 2: Get your background image. (Feel free to use this beautiful Bidoof image.)
Step 3: Turn on transparent selection, and make your “Color 2” the color that you made your sprite, and put it over the image.