A Few GIMP Tips

Bucket Fill Transparency

http://hamwaves.com/gimp.transparency/en/

Adding transparency to an Image

Below Steps can be followed for this:

- Open the Image with GIMP
- Windows -> Dockable Dialogs -> Layers
- Adjust the opacity here to slightly adjust the transparency (85% etc)

Another a large number of tutorials available here:

http://www.smashingapps.com/2013/07/30/45-useful-collection-of-gimp-tutorials.html