Ditto Dat^^^I'd put them on both sides and on the front, above the roosts. A couple across the front and up at the very top would be good.
Without overhangs you'll have to get some vents that will protect against rain....many types of louvered vents to choose from. Hopefully you could find some about 4-6" high and 12-18" long.Unfortunately I don't have much of an over hang for my coop.