If you don't want to go through the steps for downloading and setup up the software you can download the image I have setup from here. While I have done everything I can to check this is working it should be understood that you use at your own risk. If you do download the image you can skip to step 5.
Step 1: What you need
An Usb External Harddisk or a USB Drive
An Enclosure for the Raspberry Pi and Hard Disk
Wireless network card (optional)