back up to iCloud
how to back up ibook air to icloud drive?
MacBook Air, OS X Mountain Lion (10.8.3)
iCloud currently supports backing up iOS devices (iPhone, iPad, etc) but not a MacBook Air. https://www.apple.com/support/icloud/backup/
Data stored on iCloud drive exists on both your MacBook and on iCloud, but while it is duplicated it really isn't a backup. https://www.apple.com/icloud/icloud-drive/