Below are examples of how to reference a Creative Commons image.
Goddess Hathor giving an Ankh to Nefertari, by unknown, Wikipedia, Public Domain.
Colli, MG 2009, Bilbao_6 Guggenheim Museum Bilbao, photograph, viewed January 2012, <http://www.flickr.com/photos/52355315@N08/5757476385/>.
(Nefertari with Isis n.d.)
Nefertari with Isis, n.d. photograph, viewed 4 January 2012, <http://en.wikipedia.org/wiki/File:Ankh_isis_nefertari.jpg>.
Note: Use pointed brackets around <URL> with full-stop after bracket.