In this repo, you will find a series of challenges of increasing difficulty related to CircleCI 2.1 configs. There is one challenge per folder; each challenge will include its own instructions via a README.md.
The best way to follow along is to create a new repository on your personal GitHub account for the purpose of running tests. You can copy the config files from each challenge into your own CircleCI project to test if the new config works.
Each challenge will ask you to record the link to the workflow or job where you have completed the challenge.
Good luck!