While Gimp is cool, it might be confusing to a new user.
Without the aid of some tutorials, you are basically lost.

The map, Jalyha linked, is mine as has been done in PowerPoint 2010 mostly (in case you have acccess to this one..)

Also, this Little mockup here has been done in PowerPoint 2010:



It's just some basic shapes, and via the properties I removed the filling and added transparency.

If you want to try your luck with PP, you might want to go for this tutorial at first:
http://www.cartographersguild.com/tu...wing-tool.html

During this tut you are basically raising the resolution to print quality and you add some shape changing tools.



Kind regards,
Kai