Press <T_Input>[{Toggle Decorate Action}]</> while on your island to open <T_Highlight> Decorate Mode</>.

Press <T_Input>[{Toggle Inventory Action}]</> to open your Furniture Catalogue and <T_Input>[Left-Click]</> furniture pieces to place them.

Press <T_Input>[{Put Item Into Inventory}]</> while selecting a piece of furniture to put it back into your inventory.