Do you have one of the characters in there with you? Normally the first time you start the game and enter your room, there should be the cleaner in there. You talk to her, and if you promise not to tell her boss she is late to clean the room, she should go to the bed. Then you just stuff the toys in.
If you can pick the toys up and there's a character naked in the room, you should be able to use the toys on them. There's no buttons or anything you need to press to get it to work, so if you can't use them, your game may be bugged.