What are the dimensions? I'm guessing an adult can't stand up in there.
Performing chicken duties in a stooped position isn't fun at all so I would suggest raising the whole structure up about 2 feet so you can push a wheelbarrow up to the side, easily reach in, and just rake dirty bedding right into it.
I'd also would blow out that front wall and make the doorway twice as wide and install some double doors. You'll be able to swing one or both wide open for access to clean or if you want to give the coop a good airing out or if you ever need to reach every nook and cranny in order to spray for mites or such.
Cover the existing windows with hardware cloth (NOT chicken wire) and consider retrofitting some repurposed window sashes in the opening. Hinge them at the top so they swing out. They will allow fresh air to flow through the coop but keep rain from blowing in.
Check your local for sale ads for small quantities of roofing material. Often people have leftovers from larger jobs that they will sell for cheap.
It looks like the eaves are closed up so I would probably cut 3-4 circular holes in each gable about 3-4" in diameter and cover them with hardware cloth. It will give another venting option and that nice overhang will keep the weather out.
You'll want to cut a chicken sized hole in one side. I'd place it 8-10" above the floor so bedding material doesn't fall out. Guillotine doors are pretty easy to make and, with a rope fed through some eye hooks, can easily be opened and closed from outside a run. And you'll need a ramp for them to get down to the outside.
If you decide to also build a run, I'd suggest having at least a portion of it covered. Whether you have it come off the side or off the gable end is your choice and will may be determined by how you want the coop to sit on your property and whether you want a particular side to be facing prevailing winds, have sun exposure, or have the coop structure serve as a wind block for the run. Regardless of your decision, do take into consideration the pitch of the run roof and snow load (if applicable) as well as rain run-off. If you get snow in any quantity, it might be best to have the run extend off the gable end and integrate the roofline with that of the coop so that it sheds snow.
Install a couple 2x4s for roosts inside and mount a wooden crate or two on the wall for nest boxes and you're in business. You can always add external nest boxes later if you choose.
