Not really qualified to answer this
You look them up online like search acnh QR code include specifics if you need to. Then scan with Animal Crossing Items your phone or ds after downloading the app and linking it to your game. It may however be a bit of a pain as you can only scan 1 qr at one time with your telephone (sometimes I use a second phone to make the process faster if someone's I could borrow is around) and also you...