unable to run a print("hello world") in atom

hi, i have recently installed Atom in my computer.

I have followed the instruction in a youtube video on how to setup a python environment using Atom.

i've created a file with the .py extension, and the simple code i have written is print("hello world") yet I get the following error :

"python is not recognized as an internal or external command [..]"

what I have done is :

1- install Atom
2- go to setting > packages > install "script"
3- according to the video, I should be able to run code but it doesn't work on my computer.

can anybody help me please?

here is the link of the video
https://www.youtube.com/watch?v=DjEuROpsvp4