You'll first need to install deon locally in order to be able to use it.
python -m pip install deon
Once you have it locally you can run it. If you'd like to see output in the terminal you can merely run;
deon
To save the checklist to a file you can run;
deon -o checklist.md
deon --output checklist.md
deon -o checklist.ipynb
deon --output checklist.ipynb
To explore the app you can run;
deon --help