How do I set up MBL on Windows 7 to be extra hard drive storage instead of backup?

I bought a  My Book Live to act as additional storage for my laptop. I don’t want it to just be a backup of the files that are on my laptop. How do I set it up so that I can save files directly to MBL, etc.,  instead of having to copy them there and have the original still on my laptop?

Mount the drive/share as a letter. Then add the map drive/folder to any where you want in Windows.

Google for “change documents folder Windows 7”, or for pics, downloads, etc.