How to add extra option onto Product Information

Hi,
In the Magento Mall demo http://www.magento-mall.com/gaming-computer.html how do you add the customise options (E.g. Case, CPU etc)

I’ve found it in the back-end (http://demo-admin.magentocommerce.com): Catalog>Manage Products>"Gaming Computer">Bundle Items

And I’m guessing it has something to do with Catalog>Attributes>Manage Attribute Sets>Computer

But I can’t find it in there, anyone shed any light on this? Much appreciated if so.

Regards,
Rob