1. Install Python 2 ( download it from here )
    [See bottom notes about why Python 2, not 3].
  2. Open PowerShell and type python
  3. If you get an error define the environment variable to know about python

    Close PowerShell and open it again and try python again.

    If done right, you should see something like this:
    pythonHooray, we have Python 2 now installed.
    To exit Python you can type exit()

Note: Why Python 2 vs Python 3 to get started:

A programmer may try to get you to install Python 3 and learn that. Say, “When all of the Python code on your computer is Python 3, then I’ll try to learn it.” That should keep them busy for about 10 years. I repeat, do not use Python 3. Python 3 is not used very much, and if you learn Python 2 you can easily learn Python 3 when you need it. If you learn Python 3 then you’ll still have to learn Python 2 to get anything done. Just learn Python 2 and ignore people saying Python 3 is the future.

Source: https://learnpythonthehardway.org