Upgrading from Parallels 7

I am wanting to upgrade my OS X on my Mac and have been told I need to upgrade Parallels first. I have never upgraded before and am not sure how I do this since parallels is up to 11. Any help would be much appreciated of where to start!

 

Since you have Parallels Desktop 7, please purchase Parallels Desktop 11 full version, install and activate Parallels Desktop 11 as per http://kb.parallels.com/123279 and http://kb.parallels.com/123222 which would upgrade your Parallels Desktop and retain your virtual machine.