I would like to upgrade to macOS Monterey!

Is it a 2015 or later model? The model year is shown at Apple menu > About This Mac.

If it is, see instructions in How to upgrade to macOS Monterey - Apple Support

If it isn't:

A late 2010 through mid 2011 MacBook Air can be upgraded to High Sierra 10.13.6 but no later version. See: How to get old versions of macOS - Apple Support

A mid 2012 MacBook Air can be upgraded to Catalina 10.15.7 but no later. See: How to get old versions of macOS - Apple Support

A mid 2013 and early 2014 can be upgraded to the latest version of Big Sur macOS 11 but no later. See: How to get old versions of macOS - Apple Support

Is your MBA older than a 2015? Then Monterey won't work on it.

If your MBA IS compatible with Monterey, you can update by clicking on the apple in the upper left of your screen. Then click on "About this Mac". That will allow you to see if there are any updates available for you. If it says that you're 'up to date', then that means that there's nothing out there for you to update to, Monterey or otherwise.

what's holding you back? do a search on the internet for how to....