node web.js execute error

[Youth]

Hello:
I'm using windows8 and powershell, and the command fails, cli prompts as following:

PS F:\PHPnow-1.5.6\htdocs\portal_new> node web.js

module.js:340
    throw err;
Error: Cannot find module 'F:\PHPnow-1.5.6\htdocs\portal_new\web.js'
...