This page offers a run down of the basics of decorating your home, including a walkthrough on how to use the home designer function.
Decorating using your character
You can move items around your home by holding A and simultaneously moving using the left analog stick. You can only move an item backwards and forwards from the part of the furniture your holding. If you try to move it sideways, this will rotate the item instead. To add more items, you can either get them from your inventory or from your home storage.
Decorating using the Home Designer tool
You can change the layout of your furniture using the down button on the D pad and accessing the home designer function. You can use the left analog stick to hover over an item of furniture. Tap A and it will rotate the item, hold A and you can move it around. This makes decorating your house a lot easier, you won’t have to drag items of furniture around each other like in some of the older games. You can also press the + button to switch to the wall view, so you can easily move things around on your walls. When you want to remove something from the room, you can press Y. All items removed in this mode will be placed into storage, not your pockets.
If you want to pick up and move multiple items at once, you can hold down R to drag open and expand a highlight square. When you release R, everything within the highlighted area can be moved simulatenously.
You can also access your storage using the right button on the D pad and your inventory whilst you’re in this mode. This function is great for quick and easy decorating.