iCloud: Set up My Photo Stream in iCloud
Your new photos appear automatically on the iOS devices (with iOS 8 or later), 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.
On a Mac using Photos
See Use My Photo Stream to share recent photos in Photos on Mac in the Photos User Guide.
On a Windows computer
Note: My Photo Stream is not available for newly created accounts or the iCloud for Windows app (version 10). See Keep photos up to date across devices with iCloud.