How do you put demos on your Xbox 360?

I would say that you need to softmod your xbox. After you have done that, put the demo u want on a Cd-rom and enjoy the demo... It also works with full games you have downloaded. There are many guides on how to softmod your xbox, but i recommend researching a little by yourself first, because softmodding your xbox is a little risky... If you don´t do it right, your xbox could be bricked.. Hopes that is helping a little ;-)