Try:
python -V
or
python3 -V
If neither work, you'll have to go install python here.
Try:
pip -V
or
pip3 -V
Make sure the version of pip you're using is associated with the version of Python you're using.
pip3 install flask
From the root directory, set the flask app variable:
For Windows:
set FLASK_APP=analytics.py
For Mac/Linux:
export FLASK_APP=analytics.py
Finally, run the command:
flask run
And open your browser to http://127.0.0.1:5000/.