The new updates are submitted automatically when you are connected to the Internet via a WiFi connection. A notification informs you. You need to select it in order to download the file, then confirm the installation after the download.
To check manually if there is any update available, go to the All Apps section and select Settings > About the device. In the About the device menu, select Updates.
You are highly recommended to leave the device plugged in during the installation process. We also recommend you to download the updates through a WiFi connection to avoid exceeding the limits of your 3G/4G subscription.