you're likely not gonna write it yourself, and if you dont have the money to hire a service / etc to do it for you, i suggest trying to repurpose another app. for example, create a facebook account. you can add pictures, tag them, date them, add descriptions. you can connect with your group and make a shared page or whatever. or look into blogging apps. you can backup your photos via dropbox / google drive / whatever apple's shit is.