how do i update my macOS software 10.12.6

What Mac model do you have? That will determine how far you can upgrade. I believe we'll find that your Mac is not recent enough to run Ventura (13.*) – but it might be able to run something later than Sierra (10.12.*).

Select About This Mac in the Apple () menu, and look for the line that says something like "iMac (27-inch, Late 2009)". Post that here. Do not post the serial number (we don't need it, and it's not a good idea to post that on a public forum.) Based on the hardware model, we can check compatibility against MacTracker or against Apple Support pages.

Then you can use the links on this page to download a compatible upgrade.

How to download and install macOS - Apple Support