iCloud: Set up My Photo Stream
Your new photos appear automatically on the iOS devices, computers, and Apple TV you set up with My Photo Stream, no matter which iOS device or computer you use to take or import new photos. For system requirements, see the Apple Support article System requirements for iCloud.
On your iOS device
Go to Settings > iCloud > Photos (or Settings > Photos & Camera), then turn on My Photo Stream.
With My Photo Stream turned on, new photos taken with your iOS device are uploaded to iCloud when your device is connected to the Internet via Wi-Fi. The new photos appear automatically in My Photo Stream on your iOS 9 or iOS 8 device when iCloud Photo Library is not enabled. When iCloud Photo Library is turned on, they become part of your photo library and appear in All Photos. They appear in My Photo Stream on your other devices, including your iOS 7 devices, Mac computers where iCloud Photo Library is not turned on, Windows computers, and Apple TV.
On a Mac using Photos, iPhoto, or Aperture
For instructions, see one of these Help topics:
On Apple TV (4th generation)
Go to Settings > Accounts > iCloud, then turn on My Photo Stream.
On Apple TV (3rd generation and earlier)
Go to Settings > iCloud.
Select Sign In, press the center button on your remote, then follow the onscreen instructions to enter the Apple ID and password you use with iCloud.
Select iCloud Photo Settings, press the center button on your remote, select Turn On My Photo Stream, then press the center button on your remote again.