how do I upgrade my os on MacBook Pro?

galelewis wrote:

I need to upgrade my os on MacBook Pro. can't seem to find a way.

You do not specify what macOS or what Mac you are using?

If you do not qualify for Big Sur:

Big Sur macOS 11.3.1

https://support.apple.com/macos

then

older macOS installer backups on this server:

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

verify you are using the Safari browser to download/initiate the macOS links.