"GNU Image Manipulation Program"
First, note that the image has to be either GIF or PNG. If your image is
JPeG or something else, convert it using The GIMP by opening it, then
doing Save As....
Next, perform these steps with the image loaded into The GIMP. When you
perform these steps, don't fret that you fail to see the application do
Note that if you've got something pretty white on a white background (could be
another color you're selecting, so this doesn't apply only to white), the
transparency may obliterate it in an undesired way. To fix this, use the
paint can tool to change the color of the background before selecting
By Color. If you have trouble with this working, please see the
The paint can might not be too discriminating. It dumps paint to re-color
places in the image and it will often leak out over similar colors. This is
especially frustrating when you're trying to do some transparency work.
To fix this, leave selected Fill similar colors, but select Sample
merged and play with the Threshold setting: the lower the number,
the more discriminating the effect.
Read about this
Or follow these brief steps.