The function ‘Image board’ shows 2D images as 3D objects. You will need an image (png) with a transparent background.
Look for a PNG image file with transparant background to use as image board.
Go to Menu Sani | Sanitary and press the button Image bord.
Go to .custom materials in the Material library. If you want to make a new folder, open context menu on .custom materials and select add series.
Add the image > Select add material from image (right click in white folder space). Fill in the details under Material Properties if you like.
Place the image board in the room. If you want to make adjustments, use the properties in the left menu.