OK, there's the specification. Now all you need to do is write the code to do that. One way to work through it is write three different tiny scripts that each does one of the tasks. Mock up the data that may have been created by a previous step so you can focus on how to manage the current step.

Mocking up the data may be just hard wiring data into a hash or array depending on what you think may be the best way to work with the data. The important thing is to focus on just the current part of the overall job. Often you will find that one part of the task needs the data to be a certain way and you need to go back and modify a previous step, but that's OK because you are still focusing on whatever the current step is.