The second thing you need is a heat source. It is very important to keep chicks at a certain temperature range. Temperatures that are too cold or too hot will kill your chicks. There are 3 kinds of heat sources. In our brooder box we use 2 -40 watt light bulbs.
Some people use heating lamps and some people use electric or gas heaters.
If you use light bulbs or heat lamps, you should use more than one in case one burns out. The heat will give your chicks a better chance of surviving until you can replace the one that is burnt out. The 3rd part of the brooder box is the flooring or the bedding of the brooder box. You can use wood chips or peat moss, but you should avoid fine sawdust because it can clog the chicks crops which will kill them. You should also avoid cedar because it can affect the color of the chickens.