Parallels Wizard & Purchasing Windows...

I just downloaded and installed Parallels 8. I read that I can purchase and install a version of Windows via the Parallels Wizard. I go into add a new Virtual Machine, but I see nowhere for me to download/install/purchase Windows.

How do I do this?

Looking at this page I see there is a "buy windows" option, but that is not showing up for me:
http://reviews.cnet.com/8301-13727_7-57447419-263/parallels-update-adds-windows-8-support/