I have a picture of a very old house but there's a real estate sign in the yard. What software would I use to remove that sign and blend the background? I really don't want to purchase anthing expensive because it's not something I will use a alot. Its' just my Great-Grandparents house and I would like to print copies, frame them and give to cousins for Christmas.
You'd use the Clone tool in a free program like GIMP. (www.gimp.org)
There's also a GIMP plugin called Resynth that allows much easier removal of objects from images (The much-hyped Photoshop Content Aware Fill is based on it), though results vary based on the image. http://www.logarithmic.net/pfh/resynthesizer
You would use a cloning or healing tool in a regular photo editing program.
See this question for some free options: Free program for editing pictures