iPhone
On an iPhone running iOS 5 or later, go toSettings > Photos > Camera
and turn on My Photo Stream in the Photo Stream settings item. You can optionally turn on Shared Photo Streams as well if you want to share selected photos with family and friends who have Apple devices.
Mac
On a Mac running Mac OS 10.7 (Lion) or 10.8 (Mountain Lion), go toSystem Preferences > iCloud
Click on the Photo Stream checkbox then click on the Option… button. Check the My Photo Stream and, optionally, the Shared Photo Stream items.
Apple TV
On an Apple TV, follow the steps below…- Select the Photo Stream item, which is usually located near the bottom/left of the Home screen.
- At the Photo Stream Setup page, answer the question, "Would you like to turn on Photo Stream using the account xxxxx?" by selecting "Yes."
- At the Use Photo Stream as Screen Saver? page, you can optionally show your photos when your Apple TV is idle for a set time. Select "Yes" or "No."