It is not hard at all. They do all the work. You don't have to worry about temperature, They will maintain the proper temperature. You don't have to worry about food and water. They will find it in their own time. They know more about this innately than we ever will. Normally, once a hen goes...
One of my buildings only has 2 nests and just had 3 hens decide to go broody together. One hen took turns where she would spend the day. They just hatched all their charges about a week ago. Actually so many eggs were volunteered that they couldn't cover them all. Every so often I would pull...
I agree with @sourland. Just leave them alone. I think bringing the eggs up to temperature slowly is more important than worrying about settling the eggs or worrying about air cells.