I want to update my Macbook pro OS software

In older versions of OSX go to the app store and look for updates. In newer versions go to System Preferences and choose Software Update. This will take you to the newest version. Keep in mind depending on how old your computer is it may or may not support the latest update.

If you want to use an older version of Mac OSX you can use Safari to download all the way back to High Sierra.

https://support.apple.com/en-us/HT211683

If you can let us know what version you are on now I am sure those in the discussion can provide more details.

Macbook Pros have been in continuous production since 2006 and older model are restricted to older OS versions. We can neither see nor touch your computer and we are terrible at guessing! We must rely on you for details needed to give you more than a general answer.

To get specific help, please do "About this Mac..." from your Apple menu and tell us what SUB-MODEL you own.:

In macOS 10.9, the sub-model is the second line of text. The above example is for an iMac but the layout is the same for a MacBook Pro. Be sure to include any modifiers like Early, Mid, or Late. For some models those modifiers can be critical to establishing the upgrade path.

⚠️ For security reasons, please DO NOT post any serial numbers.

With that we can give you a detail upgrade path if available to your sub-model.

Thanks

To make a substantial jump, you will likely need to Install 10.11 El captain as a waypoint, Then apply all updates, including one that gives you an improved Mac App Store.

Only then can you move beyond 10.11 El Capitan with the other links in that article