After reading tons of posts, the wisdom seems to be that to keep egg production up during the shorter light months, they need about 14 hours of light a day. Because our coop is dark (no real windows) I have a 60 watt bulb on a timer from 4 am to 6 p m. The bulb is protected so that the birds can't get burned by it. They mostly free range around, but when the weather isn't so good and they are in the coop, for me and them it helps to have the light. Within a couple of days of starting the increased light, every hen started laying almost every day. Also, when they first are moved to a new place there is an adjustment period when they stop laying for a while until they get used to their new surroundings. I also mix oyster shell in with their feed. I've read some people offer a bowl with just oyster shells as a supplement for them to eat as they choose, but mine never seem to eat it that way.
Good luck and welcome!