Keep in mind that this instructable is for the beginner who doesn't know what to do after opening GIMP.
Step 1: Materials!
A computer - $600
A mouse - $10
An arm with a hand attached to it - Priceless
okay, now that you have the materials, let's get started!
Step 2: The Separation
Now click on the first color you wish to separate.
Copy this selection (ctrl + C)
click paste (or ctrl + V)
in your layers you should see a "floating layer" right click it, and click New Layer
Viola! Your color is separated! Just repeat the process for all of your colors, and you should be able to separate colors like a master in no time.