It appears that some patients do not realise either that you have to put water into the humidifier and also how to put it in.
A user manual does come with the unit but it's also easy to explain that you have use the handle to lift off the tank, turn it upside down, unscrew the cap and fill the tank with water. You then turn the tank back right way up and place it on the base.
It's always a good idea (as with anything containing water) to put the unit onto a tray or shallow waterproof container so that if there should be any leakage it will not damage the surface of what it is sitting on.
Turn it on and very soon you will be benefitting from the moisture in the air. It helps soothe dry throats, helps with blocked nose and general congestion and, according to the hospital, it also helps with snoring.