Many people make pictures and share them. They don't do this to make money but to enrich the global information well. Unfortunately not many people understand that if you publish without a proper license the works are plain copyrighted. The result is that you don't share it at all.
The opposite of what you intended!
You may want to visit Creative Commons and learn more about licensing. If you're in doubt then choose a Creatvive Commons license of type BySA which means that other people should mention your name as the original author (By) and if other people change it you don't mind as long as they share the derived work as well (SA means share Alike).