Some weeks ago I did a TDD presentation and for that matter I prepared a small tutorial of how to do it.
Details
  1. I used Robert Martin's approach to TDD.
  2. The example idea was taken from James Shore.
  3. The QueryString(built in the tutorial) component is a simple HTTP parameters parser.
Http Parameters format: http://myhos.org/test?param1=value1&param2=value2