Navigate Settings > About Phone > System updates > Download. After the update is downloaded, tap Restart now to install.
NOTE: Android is highly customizable and may look different depending on your manufacturer. The steps below may vary for different devices.
1) Open Settings.
2) Tap About Phone.
3) Tap System updates.
4) Tap Download.
5) After the update is downloaded, tap Restart now to install.
Your device will be updated to the latest version of Android.