Go for it Loghousemom! You can probably pick up windows at one of the Habitat re-store - or - keep an eye out for someone having windows replaced and ask if you can haul away a few of the old ones.
It's a challenge but very rewarding to learn to do these 'construction' things.
We don't have anything like a habitat re-store around here, but I do have lots of old windows from when we replaced the ones in our house that I want to use, and then have a prop to open them. Right now my coop has large windows with screens, so I could just take the screens out and recover them with hardware cloth to get a bit more airflow.... I think I might save the window project for next summer. I am working on repainting the trim on the coop and insulating the inside for winter now. That and replacing the fencing that was burnt in the fire last fall, I am plenty busy.