Here is a great video tutorial that walks you through the entire process (it's in German but is very easy to follow without the sound.) From http://katzenkram.blogspot.com/2012/02/kamsnaps-mit-stoff-uberziehen.html
A step-by-step written tutorial with pictures is also available, courtesy of See Suzie Sew, at http://www.kamsnaps.com/How-to-Make-Fabric-Covered-Snaps-43.html.
If you decide to try your hand at making your own fabric-covered snaps, we'd love to see them! Pics can be emailed to sales @ kamsnaps.com (remove the spaces), and we'll be happy to link back to you.