How to hook up a server room?

I’ve heard of server rooms grown out of spare computers. I am computer-savvy but don’t know much about how server rooms are set up. I do have a spare machine running a web server that stores personal files, but it’s a very simple setup and I’m interested in learning more advanced stuff.

Could someone please tell me, from beginning to end, how to a server room is set up? I’m talking about the stereotypical server rooms you see, such as this one here: http://en.wikipedia.org/wiki/File:Datacenter-telecom.jpg