Back up your Mac with Time Machine or another backup method
Check your Mac model and current macOS version
Confirm the new macOS version is compatible with your Mac
Connect your Mac to power
Connect to a stable Wi-Fi network
Open System Settings
Click General
Click Software Update
Wait for your Mac to check for updates
Click Upgrade Now or Update Now if a new macOS version is available
Enter your administrator password if prompted
Agree to the terms and conditions
Wait for the download to complete
Allow the installer to prepare and restart your Mac
Follow the on-screen installation steps after restart
Keep your Mac plugged in and do not turn it off during installation
Sign in after the upgrade finishes
Check Software Update again for any additional updates
Restore files from backup if needed