This is the deal: start from "001_xxx" and then move forward to "002_xxx". It is up to you to guess the third step!
This repo contains practical Docker tutorials only, if you want the whole theory then you may want to consider a think book about the argument.
Before you start be aware that I am no expert: I use Docker to make my developer life less messy. So far so good, and you can easily achieve the same level of satisfaction and pay me a beer!