Mine are in storage but it's fairly straightforward. They create an ultrasonic wave that breaks the water above into vapor. The focal point is usually about 2 inches above the plate. They splash a lot of water around, but you can always put a cover over it if you just want the fog to get out.
Don't put them in a spot where your pet can accidentally get their body over the fogger. Getting your finger caught in the wave can be quite excrutiating (tested on two different people

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Although above the surface of the water it's harmless.