Creating a large background and moving it with your finger

I am designing a Game and have a large background. The background it a lot bigger than the phone display so the user will only have a small "View" of the background. They will be able to move around开发者_Python百科 by scrolling with their finger.

How do i go about this?

My application does this.
It is open-source so feel free to copy-and-paste:
http://code.google.com/p/androidbigimage