How do I create a colour theme in VS Code

Question

The Visual Studio Code website says in this link: https://code.visualstudio.com/api/extension-guides/color-theme#create-a-new-color-theme that I'm to "Use VS Code's Yeoman extension generator to generate a new theme extension." then it shows me what I'm to type in:

npm install -g yo generator-code
yo code

The problem is, after typing it into the terminal, I get this message:

npm : The term 'npm' is not recognized as the name of a cmdlet, function, script file, or operable program. Check the spelling of the name, or 
if a path was included, verify that the path is correct and try again.

Have I typed it into the wrong place, or have I made a mistake somewhere else?

I followed the previous step and it seemed to be working so I'm confused as to where I went wrong. Thank you for helping.

Answer 1

Make sure to add node.js path to PATH environmental variable.

Open cmd as Administrator and type

setx /M path "%path%;C:\path_to_node.js"

Usual, Node.js is found at C

Anyway, it should be already added on PATH upon installation of Node.JS.