Point your web browser at
http://www.theezreader.com
Select the SUPPORT tab and then select FIRMWARE DOWNLOAD.
The instructions are listed there as well as the most current firmware files.
The firmware is about 90 MB in size and is a compressed .rar file. After downloading it, you will need something like 7zip (windows) to decompress the .rar. file into a 130 MB file called setup.bin
Copy setup.bin to the root of the SD card and follow the instructions. I had other stuff on my SD card and it worked fine, so the card does not have to be empty as long as you have room for the setup.bin file.
Note that when it is running, the upgrade will list each thing it is upgrading and it will draw a progress bar across the screen.
Good luck