The update can be set to automatically download in the background and you should receive a notification once it is available for your device. You can also manually check for the update availability by heading to Settings > Phone Update > Check for Updates.
Make sure your battery is fully charged and that you are connected to a Wi-Fi connection before initiating the update, which should take around 10 - 20 minutes to complete. Once the update is completed the phone should restart one last time before it is ready for use.
The full change-log of the GDR2 + Amber update for the Lumia 928 follows:
Key Device Enhancements:
- Silence your phone easier with Flip to Silence audio feature
- Make assisted calls more easily while roaming in select international destinations
- Select, download and pin music easier with the Xbox Music Experience
- Access song and album information more accurately with the Xbox Music Experience
- Enjoy better web browsing with improved HTML 5 compatibility in Internet Explorer
- Connect with greater stability when using Voice over Internet Protocol (VoIP) apps like Lync and Skype
Newly Supported Capabilities:
- Group Text; Note: This feature is off by default, but users can configure via the Messaging application by selecting Settings, Group Text, and changing the toggle to On.
- IMAP for email, CardDAV for contacts and CalDAV for calendar when setting up aGmail account
- Easily change advanced settings like shutter speed and light exposure on Nokia Pro Camera (Nokia Pro Camera available for download from the Windows Phone Store)
- Updated Display+Touch Setting; Adjust the color profile of your display; Check the time more easily even when the phone is in idle mode with Glance Screen
- View how your phone’s memory is being used and clear temporary files with StorageCheck
- Updated audio settings, letting you silence the phone’s ringer just by turning the phone face down
- Improved texting performance and Bluetooth connectivity
[NOTE] Lumia 928 hardware doesn't support FM radio.
source - Verizon