npm install
npm start

You can then view the tests in your browser at http://localhost:4444.

When you visit that page, all of the tests should be failing; your job is to get the tests to pass. To do this, you'll need to refer to the tests in the files in the tests/app directory, and edit the files in the app/ directory. Once you update a test, you can reload the test page in the browser to see whether it worked.

You can also run (most of) the tests on the command line:

npm test

You can also develop with live-reload and grunt-watch if that's your thing:

npm install -g grunt-cli
npm install
grunt develop