My great Win 7 PC burned up this past winter, so I got an HP all-in-one, but with no option other than 8.1; I had the local shop do the Classic Shell thng, but I'm still less than impressed.
Batavia be a bit nervous about the next steps....
You have Win 8.1 and you want to know what to do to get
Win 7?
you really dont have to do nothing the system notifies you
what to do and at some point it will ask you to install it.
Its all self explanatory and if by chance my explanation is not good enough you have a year to figure it out otherwise.
Better than that, when someone comes by the house who knows better than you, ask them to lend you a hand.