A: Just put a couple of drops (literally just a couple) in the humidifier in the center of the lid. You'll see the green sponge absorb it. Since the case is airtight, very little water is needed. If you're only keeping cigars in it for a few days, and they're humidified when you put them in, you could probably get away with adding no water at all. For longer-term storage, I'd recommend adding a couple of drops of distilled water every 2 weeks.