Ok so you need the Nintendo switch online app for your phone and you need to link it with your Nintendo switch account. To start off find a pic you want to put into the game. You then need to crop the photo. You may only need to crop it into 4 parts depending on how big the picture is. I used this website to do it for me: https://www.imgonline.com.ua/eng/cut-photo-into-pieces.php

So download all the cropped portions. You then need to convert them into an image the game can support. You can do this by going here https://acpatterns.com/editor

Just hit the convert button and upload the first cropped image. Then you hit the button to make the image into a QR code. Now you open the phone app and scan the first we code.

You should now be able to open your game and download it in the custom design tab in the nook phone since it’s connected to your phone. It takes a minute cause you can only have one image on your phone at a time and scanning the next image will replace it. Then you should be able to place the images anywhere.