How do I use Photoshop to have an image such as a logo seemed to have been made up

[jack m]

of smaller pictures? Okay I think we have all seen something printed on paper that if you see it close up the main image is made up by smaller pictures, but as you see it from a distance you can see the whole complete image as one. I need a good and easy tutorial on how to do this using Photoshop. Thanks in advance!