Usually I worked with open-source software PAINT.NET or FastStone Image Viewer for editing images on a very fast and easy way. I had a trie-out with GIMP (GNU Image Manipulation Program). Fans and freaks of GIMP dreaming of and saying that it is the free equivalent of PHOTOSHOP with a massive range of functions.
Finally I’m absolutly convinced about it. Here is my first try.
Update 14.09.2013: This article was published in The Daily GIMP News on 13th September, 2013 as well. That’s pretty cool! 🙂