I wanted to do the simplest of things yet still the wheels have come off

Visual view, Registry, Feature independent (box checked). I want to define a new key in : HKLM/Software/Microsoft/Windows/Currentversion/App Paths. I navigate to this in source keys. When I right click on 'App Paths' I don't get a new key option only an option to refresh views.
What am I doing wrong here ! I've gone through the help file instructions 3 times but no joy.
It would probably be just as easy to 'Write Registry' in MSI code view but this is the first key I've ever tried to define and I want to see where IA inserts it into the script.
Thanks and best wishes
Pete B.