Using this dispenser is easy. First, if you choose battery power, insert 4 AA - size batteries (not included) into the dispenser. Or, you can use the optional AC adapter (72 - ACA, not included). Once it's powered, place your hands under the sensor zone. The dispenser will automatically give you a single shot of liquid soap or hand sanitizer. As for the supply tank, it's under the vanity. You can easily see the contents level through the clear tank with graduated markings. When it's running low, just refill it. The indicator LED on the dispenser will let you know about the battery condition, contents level, and if the sensor is working. To keep it in good shape, clean the exterior of the dispenser with a soft, damp cloth regularly. Make sure not to use abrasive cleaners as they can scratch the satin finish of the Type 304 stainless steel body. Also, keep it away from water splashes and direct sunlight to avoid any damage to the battery or the internal mechanism.