Make sure that you have downloaded the latest Philips Hue app and set up a Hue account linked to your hue bridge.
Go to the 'Settings' > 'Software update' and follow the onscreen instructions. The Philips Hue app will tell you if you are up to date or if a software update is being downloaded.
A notification will appear when new software is available for your Hue bridge or Hue lights.
You will receive a notification in your Philips Hue app to upgrade your system.