You can customise your furniture with all the textures available in the Decorate menu.
Select a texture, then click on the object or the part of the object that you wish to decorate.
You may need to zoom in significantly if the object that you want to decorate is small or is surrounded by many objects. This also allows you to avoid decorating a wall by mistake.
Don't forget to do each side of your piece of furniture!
Tip: To avoid decorating a wall while you're decorating an object, you can Enable wall transparency in the toolbar.