What is it?
It's a simple script that can (and should) be used to run/test WordPress themes. It has some default content to partially make you're theme usable (and testable). This is not WordPress (it just works like it)
How to use?
Simply drop the project into any WordPress theme and that theme should work as a full website running WordPress. Yes, you can use it to replace you're WordPress installation, but I wouldn't recommend it.