I can't figure out how to update my macbook. If I go to system preferences nothing comes about about a software update. When I go to the App store to see if there an update there I also can't find it

To be clear, software update generally means to install software that revises the macOS currently running on the Mac; update Catalina 10.15.1 to Catalina 10.15.7, for example.

To update your current macOS, click the Apple  icon > About This Mac and then click Software Updates.... If there are any updates available for your Mac, they will be listed and you can apply them when you like.  Software updates may be set to occur automatically.  If no updates are presented, then it may be assumed that none are available for your current OS.

A software upgrade is usually a generational step up to a newer macOS; upgrade from 10.13 High Sierra to 10.14 Mojave, for example, or from 10.15 Catalina to macOS 11 Big Sur.

Upgrades do not happen automatically. They must be initiated by a user with admin privileges.

❗️ Do NOT upgrade until you have made a Time Machine or other backup of your startup drive.

Learn How to Back up your Mac with Time Machine

How to Upgrade  macOS:

The macOS version you can upgrade to depends on the year your Mac was released.

Click the  (Apple) menu at the top of your screen and choose About This Mac.

Check the Compatibility of your Mac with newer versions of macOS:

➡️ macOS 10.14 Mojave is compatible with the Macs listed here

➡️ macOS 10.15 Catalina is compatible with the Macs listed here

➡️ macOS 11 Big Sur is compatible with the Macs listed here

➡️ macOS 12 Monterey is compatible with the Macs listed here

❗️ – IMPORTANT – Your 32-bit apps won’t work in Catalina, Big Sur or Monterey.

https://support.apple.com/en-us/HT208436

Use the free utility Go64 to check the compatibility of your apps:

https://www.stclairsoft.com/Go64/

✅ - IF your Mac and apps are compatible, then using Safari only, download the macOS upgrade installer app:

Click >  Mojave,  Catalina,  Big Sur  or  Monterey.

Once downloaded, double-click the “Install macOS…” app in the Applications folder to begin the upgrade.

The App Store Updates page only informs you of updates available for the OS you are running.

System Preferences> Software Update did not come to macOS until macOS Mojave 10.14 was introduced.

Installing a newer OS is called an upgrade.

Which OS you can upgrade to will be governed by which model and year your mac is.

Click on the  top left of your screen click on About This Mac to find out the year of your mac.

For Mojave, Catalina or Big Sur,

Open Safari and click on this link, 

How to get older versions of macOS

Go to Check Compatibility to see if your mac qualifies for the OS upgrade you want.

Then go to the Use Safari to download macOS section and click on the OS you want to install.

Before upgrading make a full back up of your Mac.

Check that third party apps you use have updates available for the new OS.

https://roaringapps.com

Check that your printers/ scanners etc have updated drivers and software available for the new OS.

Connect your mac to your router via cable rather than rely on WiFi.

Do not use your mac while it is downloading

and do not use any other devices that share the same internet connection.

If the App Store says ‘Open’ then it is detecting a previous download of the install app

go to the Applications folder locate Install macOS ******.app.

Move it to the Trash, empty the Trash.

Restart, click on the link again, the App Store should say ‘Get' or 'Download'.

If you want to or are able to upgrade to Monterey open Safari and click on the link below,

How to upgrade to macOS Monterey – Apple Support (UK)

If you are considering upgrading to Catalina, Big Sur or Monterey be warned they do not support 32bit apps.

Your Mac is probably running 32bit apps and these will need to be updated to 64bit apps,

some updates may be free, some may be paid. Use this free app to discover which apps you have

are 32bit, https://www.stclairsoft.com/Go64/ then contact the developers of the software to see

if they are offering 64bit updates.

See if this helps: https://support.apple.com/en-us/HT211683

The ability to upgrade will be governed by the age of your MacBook.