Node.JS: Why is my connection to localhost:3000 refused?

I downloaded a pdf book about Node.JS from sitepoint called: "Jumpstart Node.JS". In following the instructions to set up the server on the command line, install the dependencies, and navigate to localhost:3000, i got nothing except the following message: "Connection refused: localhost:3000", Can somebody please tell me what might have went wrong and how to fix it?

via Mathys Taljaard