These screencasts show how to use CumulusCI from a command line.
For a live demo with voiceover, please see Jason Lantz’s Pycon 2020 presentation which gives more context about CumulusCI from about minute 36 through minute 54.
This screencast shows how to initialize a fresh CumulusCI project:
The next one shows how to use CumulusCI to retrieve Metadata from a Salesforce org and save it in github.
The next screencast shows how to use CCI to manage sample or test data.
The final screencast shows how to customize CumulusCI flows and how to use CumulusCI for QA.