iCloud: Apple ID
If you already have an Apple ID, you should use the same email and password to set up iCloud on each of your iOS devices and computers.
To see which Apple ID you use with iCloud, do any of the following:
On your iOS device, go to Settings > iCloud.
On your Mac, choose Apple Menu > System Preferences, then click iCloud.
On your Windows 8.1 computer, go to the Start screen, click the down arrow in the lower-left corner, then click the iCloud app.
On your Windows 8 computer, go to the Start screen, then click the iCloud tile.
On your Windows 7 computer, choose Start menu > All Programs > iCloud > iCloud.
For more information, see the Apple Support article Using your Apple ID for Apple services.