I have an iPhone I inherited from a friend. I think it is an iPhone 3. On the Settings | About screen, it shows the model number as MB716LL/A. The Version, which I assume is the OS version, says 6.1.6 (10B500).
I tried to download the Dropbox app so I could upload some photos. I was told that I need to upgrade to iOS 7. I can't figure out how to do that. Can anyone help?