how to run geometry setup script of gengeo? (simplebox.py)

Dear Sir,

I am new user to this software. Please help me to start my work. I have little knowledge in python.

I am trying Gengeo examples which is given in tutorial (simplebox.py). I have typed this file in text editor and saved as filename.py. Now I want to run this file to construct geometry. Can you please help me how to run filename.py. I typed python filename.py in terminal. It is showing invalid syntax.

I dont have knowledge in making geometry. Please encourage by replying to this mail.

Regards
Divya