Click on the clock at the bottom-right of the Taskbar (shelf) to open the Control Panel.
Next, click on the gear icon to open the Settings App.
In the Settings App, scroll down on the left and click on “About ChromeOS.
If you see a button called “Check for Updates”, click it to begin the update process.
Once the update has been downloaded, you will be prompted to restart the ChromeBook and the update will be complete.