Most people who have started skinning have heard of the "Remove White" filter. This is something that is used by the Photoshop line of programs and is useful for making a quick template.
Gimp also has the capability to remove white or any colour we want from a void file. At the very end of this tutorial, I'll show you how to remove a colour other than white.
Step ONE
To begin, open the void file that you want to get started with. The example I use in this tutorial is the A6M. The first thing that needs to be done, is converting the void from indexed mode to RGB mode. Click
Image->Mode->RGB.
Step TWO
Now the actual colour removal process begins. Click
Layer->Transparency->Colour to Alpha. This will bring up the
Colour to Alpha window. If you click the coloured bar (which is white in this example) you will get the
Colour to Alpha Colour Picker window. Using this you can choose any colour that you need removed. We'll get to that at the end of the tutorial. For now, we'll choose the whitest white we can, which has an HTML notation of FFFFFF. Now Click OK.