How to write program and work in python using in computer python shell

Question

I want answer with examples .

Answer 1

You just write it with a text editor, then save the extension be .py.
Then run from command line: python yourfile.py
On unix os, the python is already installed.
But on windows you must download and install.

Answer 2

you dont

Answer 3

I 'll try ..

Answer 4

thanks dude