ATDD is an interesting thing. By using our step definitions to begin designing
our object model we can can provide a GPS for our test driving.

To do this kata:
1) Define the steps for a feature (make up the object model in your steps)
2) Run your features
3) Test drive to remove the first exception/error you get.
4) Repeat until the feature turns green.

I would recommend rspec for your tdd framework.