It all seems so confusing.
confusing! And will only get more so!
One easy way to find images you are free to use in your work is to use Flickr's advanced search features and limit your search to: "Only search within Creative Commons-licensed content." http://www.flickr.com/search/advanced/?
If you are writing for publication, you may also want to check off "Find content to use commercially." (Though, just to make things confusing, if you're writing for Zymurgy, it's a publication published by a nonprofit, which I believe would be noncommercial use--unless you are paid for the article, in which case it's commercial use. Anyone with a better take on that is encouraged to chime in.)
So this picture can be used for commercial or noncommercial use, as long as you provide attribution:http://www.flickr.com/photos/mat_the_w/3698716702/
Click on the "License" link on the right-hand side of the photo page to see the Creative Commons license.