title: Getting webpage pictures to overlap scroll
body: <p>I'm doing the <a href="http://www.freecodecamp.com/" rel="nofollow">Free Code Camp</a> thing and the first Zipline challenge is to replicate the following webpage on <a href="http://codepen.io/ThiagoFerreir4/full/eNMxEp/" rel="nofollow">Code Pen</a>. What I'm looking for is a hint or two in the right direction so I can get the pictures to scroll like they do on the webpage. I don't want the answer(s), just a hint or hints in the right direction so that I can do my own work. I think I'm suppose to use CSS, and if that's the case I have no idea which property/properties to use, maybe one of the <code>background</code> properties?</p>