macOS Monterey 12.3
HOW DO I DOWNLOW macOS Monterey 12.3
MacBook Air 11″, macOS 11.7
You would download it from the App Store.
Note: Only the last model of the 11 inch MacBook Air (the Early 2015 model) is capable of running Monterey.
You've also posted to the wrong forum area, the MacBook forum area instead of the MacBook Air forum area.