Kudos if you can recommend a good free program. Cheers.
http://www.gimp.org/
The GNU Image Manipulation Program, linked above, has been compared to Adobe's Photoshop or Corel's Paint Shop Pro in terms of features by some of its users. I personally don't use GIMP, as I have a different software I stick with, but I've seen the results those users have produced with it. Based on that and word of mouth, I'll give it my recommendation as a good free program.
The site's documentation section has a variety of language options for its manual, and a list of tutorials to help learn the software.