I'm trying to set up my command prompt to execute my Python code. I downloaded Python, but it's not showing up in my System Variables. And to add on to that, I don't know how to add System Variables because the buttons are all grayed out: 

[![enter image description here](https://i.stack.imgur.com/imLyi.png)](https://i.stack.imgur.com/imLyi.png)

Am I doing this wrong or am I totally on the wrong track?