Keep getting message 'No boot device is available'

I'm not quite sure I understand what I'm doing wrong. Do I need a to buy something else in order to run windows? It sounds as though I have to buy a windows disk or something of that matter. I'm having a tough time getting this running and I'm not sure what to do. Can I use a regular flash drive or is there a certain process I need follow? Thanks!

 

Hi GusD
The purchase of Parallels does not include Microsoft Windows. You will need an .iso image or installation disk to install Windows.
Instructions for installing Windows using Parallels: http://kb.parallels.com/en/4729