Users will receive a message on their phones prompting them to get the update. All they need to do is to connect to their computers via Zune for PC, or Windows Phone app for Mac, and follow the on-screen instructions.
Besides getting major system updates like the new Smart Screen with resizable Live Tiles, there are also several new features introduced to the Nokia Lumia devices. They are:
Delivery of the update is operator dependent, hence you may receive the update at a later time after the telco in the country has approved it. You also can manually check for the update via Settings > Phone Update > "Notify me when new updates are found".