Do i even have to describe What vBulletin is ?
Ok then if you know what that is you can download it completely free from here
Installing vbulletin is different from anyother thing
After uploading go to /includes/config.php.new
Rename config.php.new to config.php
Edit the file using notepad++ or anyother text editor
The document is commented very well and you should be able to understand the things
the password is : nulledbb.com