NodeWebkit fails to load PhantomJS module

i have never built a nodejs application, but i watch some videos on building a website based on ExpressJs that runs on top NodeJs, after that i discovered a nodejs module called Node-Webkit that let you build HTML5/CSS/JS application that runs on your desktop, i have seen some videos about it, and then i read somewhere about PhantomJS/CasperJS, a library that let you test your Javascript, and you can benefit from it by building bots, i have write some scripts about automating some tasks and it works great.

My mission here is build a bot with javascript using (NodeJS), which works on desktop using (Node-WebKit) receiving inputs from the GUI generated by (Node-Webkit) and pass it to PhantomJs functions to do the task.

I have write a simple html page to test PhantomJS if it is working.

<html>
<head></head>
<body>

    <h1>hello world !! :D </h1>
    <script>
        var page = require('webpage').create();
        console.log(page);
    </script>
</body>

after that i drag and drop nodewebkit, my project folder contains index.html (code above) and package.json.

and this the error that gives me

  Error: Cannot find module 'webpage'