The primary tools and/or skills needed to accomplish this effect are:
If you need a refresher on these tasks, see the tutorial links from About.com Graphics Software accompanying this step-by-step tutorial.
Inspired by an Instructables tutorial by Andrew546, I created this tutorial using the free GIMP photo editing program. It was the very first time I've ever used this software. I highly recommend it as an alternative to programs such as Photoshop or Photo-Paint. Although the instructions in this step-by-step tutorial are for the GIMP for Windows, you can accomplish this same effect in other image editing software.