Can't create subtheme

I can't create a subtheme. I'm not sure if I've done all the other command line stuff correctly. I get lost trying to run commands when I don't know which directory I should be in when I run them.

To copy my command line errors here would take up to much space. But briefly I've installed:
-the theme using the Drupal install theme interface
- sudo npm install -g yo generator-aurora

When I try to create a subtheme the instructions say: "within your theme folder, run..." but is this my sites/all/themes folder or inside Aurora folder, or maybe I create a subtheme folder and then inside that run the command. I tried both the themes folder and inside Aurora folder and "yo drupal-theme" gets me:
module.js:338
throw err;
^
Error: Cannot find module './build/Release/shell'
at Function.Module._resolveFilename (module.js:336:15)
at Function.Module._load (module.js:278:25)
at Module.require (module.js:365:17)
at require (module.js:384:17)
at Object. (/usr/local/lib/node_modules/generator-drupal-theme/node_modules/execSync/index.js:30:11)
at Module._compile (module.js:460:26)
at Object.Module._extensions..js (module.js:478:10)
at Module.load (module.js:355:32)
at Function.Module._load (module.js:310:12)
at Module.require (module.js:365:17)
at require (module.js:384:17)

So I'm lost and any help is appreciated. I can't believe this stuff isn't easier by now.