iCloud Photo Sharing lets you easily share photos with other iPhone and iPad owners in what's called a shared Photo Stream. Once you create the stream and they join it, they can view, comment, and like any photos you add. And, if you like, you can even let other people add photos to your shared Photo Stream. It's great for family and friends, for vacations, and for sharing pictures of the kids.
How to allow other people to add photos to your shared Photo Streams
Launch the Photos app on your iPhone or iPad.
Tap on the Shared tab in the bottom navigation.
Tap on the Sharing button in the top left to navigate back to the main list of shared Photo Streams. By default the Photos app loads the activity stream.
Tap on the album you'd like to allow others to add to. Remember that it has to be a stream you own, not a stream that was shared with you.