Attribution is when you name the authour/creator of a work. To be named as the creator is one of the rights imparted by copyright.
When using a Creative Commons licence you are always required to attribute. The way you do this is that you in a visible place, close to the licensed work, put the name of the creator – preferably with a link to the original work, and the CC licence, together with a link to the licence website.
Here I have used Open Attribute‘s add-on to copy the licence code and then I pasted it in the ‘caption’ field when uploading the photo to WordPress. In this way I managed to fulfil most of the CC licence requirements: the attribution is close to the work: check, the licence is included and linked to: check.
But I also wanted to include the name of the photographer, which was not included in the OA code (they only had the title of the photograph). So I simply added the name of the creator first in the photo’s caption and linked the name to his Flickr photostream. Without the Open Attribute add-on it would have taken a bit longer to link, and it would have been even quicker if they also included the name of the creator, but you can just as well do this with the usual html-links.