A:
To fill this humidifier:
First, remove the rotating nozzle (conical in shape, at the top, white in color).
Then, remove the water reservoir and turn it upside down. There's actually an carry handle shaped into the reservoir which is accessible when it's upside down.
Fill using distilled or filtered water by removing the screw off cap (remember: left loosy/righty tighty - no need to press it or squeeze any sort of release).
Now; reverse the instructions:
Put the cap on. Turn it right side up and place newly filled reservoir into base. Once reservoir is secure in the base add the nozzle.
Don't forget - make sure it's off and unplugged when filling/removing base.