You need a Thermometer/Hygrometer ( measures the humidity). They are placed inside the incubators for the readings. Ranges for humidity are usually kept in the 40 to 50% range the first 18 days and 60 to 70% range the last 3 days of incubation. The Thermometer part reads the temps, the Hygrometer reads the humidity.
Thermometer/Hygrometers can be purchased at Walmarts, some brands are Accurites and Springfields and Bemis. They are in the garden sections of stores along side reg. Thermometers.
Water wells or troughs as they are called are in the bottom plastic liner of the bators. I usually keep the middle section ( C trough ) filled for the first 18 days and then all the troughs the last 3 to bump the humidity to the correct level.