This was a very challenging accomplishment for me. I tried to mimic a PS tutorial, but with a different method for creating the globe. The difficult part was not creating the sphere, but turning it somewhat transparent. I was really new to GIMP when I attempted this, but I think I did alright. Hope you enjoy it.
The tutorial is in html format. Just download the zip file to your hard drive, double-click to open, extract to your desktop (or some other convenient location) and double-click on the html file. The tutorial will open up in your browser.
Let me know if you have any questions or need additional information.