When I try to upgrade my computer it says there are no updates available

The model year of a MacBook Pro is available at Apple menu > About This Mac.

An Early 2008 through mid 2009 MacBook Pro can be upgraded to El Capitan 10.11.6 but no later version. See: How to get old versions of macOS - Apple Support

A mid 2010 through late 2011 MacBook Pro 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 through early 2013 MacBook Pro can be upgraded to Catalina 10.15.7 but no later. See: How to get old versions of macOS - Apple Support

A late 2013 and mid 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

An early 2015 or later can be upgraded to the current version of Monterey macOS 12. See: How to upgrade to macOS Monterey - Apple Support

Software Update won't offer an "Upgrade" after a while. It will only offer updates which will only be for the version you are running.

You need to go to the Mac App Store to install the Monterey upgrade. Other, older OS versions were linked by FoxFifth and tjk if you cannot run Monterey on your Mac.

Hi,

Go to the Apple Menu > About This Mac to see exactly which Mac you have, then find out if it is compatible with a newer OS here: How to get old versions of macOS - Apple Support