I stopped by a garage sale two years ago that had windows for FREE. I picked up four windows. I've been using them on 'lean-to' boxes until yesterday.
I began attaching the windows to the frame of the green house. I will likely have to finally purchase some material for the greenhouse to put on a roof and door.
Yesterday, I was able to get the southeast and southwest facing windows in place. There are several things I'll need to work on to make it a functioning greenhouse.
More updates to come as the project continues. Thus far, I've used only leftover and salvaged material and hardware.