Do so by tapping the grey gear icon on one of your Home screens (it might also be in a folder named "Utilities").;
,,, It should turn green, meaning that you can now do the following things:


Share selected photos by tapping the share button in the bottom left corner of your screen, then selecting iCloud Photo Sharing below the "AirDrop" section.
View your shared photos and other users' photos that they've shared with you by selecting the "Shared" tab at the bottom of the Photos screen.
Open your iPhone's Settings.
Scroll to the fourth group of options and select iCloud.

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Select Photos.

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Slide the iCloud Photo Sharing switch right to the "On" position.
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