show it, talk to kilton. and if you say the right words. kilton will disappear to the outside of gerudo town. after you shown the photo to the man at the stable, youll recieve 100 rupees and your sidequest will be complete. then, head to gerudo town and search outside the town until you see kiltons shop. the shop is only open at night. and inside the shop is dark links tunic which is expensive...