From time to time, software updates for your phone. Your phone can notify you when the update is available Check for updates. Then you can install the downloaded software update to your phone.

Note: Checking and downloading phone software updates from your mobile operator may incur additional data transfer charges apply.

Depending on the type of update, the update may erase all your personal data and customized settings, and also remove any applications you've installed. The information you want to store and make sure to back up files. For details, refer to the phone data backup issues.
When an update is available, it will display the Install system software update dialog box. Select Install now and then tap OK.

Wait for the completion of the update process. When the update is complete, the phone will automatically restart.

Phone to manually check for software updates

On the Home screen, press MENU, and then tap Settings.
Scroll down the screen, and then on tap Phone> System software updates.
In the System software updates screen, tap Check now.