Back up your Mac with Time Machine or another backup method
Check your Mac model’s compatibility with the new macOS version
Connect your Mac to power
Connect to a stable Wi-Fi network
Open the Apple menu
Click System Settings or System Preferences
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
Follow the on-screen instructions
Agree to the terms and conditions
Wait for the download and installation to complete
Keep your Mac plugged in during the entire process
Allow your Mac to restart as needed
Sign in after the upgrade finishes
Check for any additional software updates after installation