Who can I contact about 4chan /b board?

Hi, recently became a fan of kevin smith and became fascinated with his exchange with the westboro baptist church during his redstate tour. I followed some WBC members on twitter so that I could follow their exchanges with kevin smith. Through that I became aware of a group called anonymous and became interested in what they stood for. during my research I learned that the anonymous group came from 4chan on what is called the /b board . Tonight I checked it out and found the site to be a rather cheap looking cluttered list of pics and comments of various things. As I scrolled down I saw what appeared to be child . At first I thought it had to be photoshopped but judging by the comments calling for moderators I umed that it was real and felt sick. Who can I contact about that site? It surely is not legal and whoever posted that picture is obviously abusing a child.