Update macOS in System Preferences
You can update macOS to a newer version for free, in System Preferences under the Software Update panel.
Click "System Preferences..." under the Apple menu
In System Preferences, locate & click "Software Update"
Check if any updates are available and consider installing
Install any incremental updates for macOS. They typically provide security updates and important bug fixes. An example of an incremental update is when your system is currently running macOS 11.6.1, and an update to macOS 11.6.2 is available to install.
The same panel will also offer to install new versions of macOS (as shown above). These updates may potentially be disruptive to your workflow, since some apps may no longer work in the new version. Although we strongly recommend that you keep your Mac up-to-date; if you are unsure about installing a new version of macOS, please contact tech support.