1. Download the ISO file from for the version you wish to install. 
  2. Next right click on the ISO file and select Burn disc image.
  3. Then on the next screen select "Verify disc after burning" and then click Burn. 
  4. Once the drive is written and verified you will get the screen below.
  5. At this point attach the USB DVD drive to the appliance. During boot up go into the BIOS and verify the DVD drive is the first in the boot sequence.