How to create a popup page as a model window, which appears on the welcome page.Until I close the popup window i should not allow the user to access the welcome page.

Eg: we can see the same functionality in the Gmail Documents.

we would like to implement in JSF/AJAX/JavaScript.

Any sample code is much appreciated.

Thanks,
Prakash

try this link. This is a good position to start, next you can modify according to your need.