I used a program to modify my pictures, but was not always pleased with the result.
Gudveig N. H. has very good pictures on her blog, and uses Corel Paint Shop Pro Photo , but it costs a bit of money.
Grethe's Flittige Hender posted a comment on my blog where she recommended Picasa from Google, a free program.
I have now tried it out, and are very happy with the results! Thank you for your help!