How do I upgrade Monterey 12.7.6 to MacOS 13?

macOS 13 Ventura requires a 2017 or later iMac.

Yes, Monterey is the latest supported on a 2015 iMac. As long as they work you can keep using it.

Yes, you can continue using your 2015 iMac however please remember it is over a 10. years old and is considered obsolete and vintage. Obsolete means it will not run current versions of Mac OS and other third party software you may have, vintage means that parts are difficult to come by in the event of a repair and Apple (an Apple Store for example) will not work on it.

My recommendation is now is the ideal time to begin researching and planning on replacing the replacement of a 2015 iMac as it is now living on borrowed time. If this is something you intend to do and could use assistance selecting a replacement Mac please let us know and we can assist. Apple also has released a site that helps too, the Mac - Which Mac is best for me? - Apple is a good place to start.

Please read How to update the software on your Mac - Apple Support.

How do I do this?

I have a 2017 Macbook air, and the Ventura (which I need to download the Microsoft Teams app in order to transfer my skype contacts) won't download. Should I just find some other Skype substitute that will work on my computer?

Try the free, open source alternative to MS Office, LibreOffice. It can open, edit and save Office files in its own format or the Office format for sharing.

Also Apple's Pages and Numbers can open Office files, edit them and export to the same Office format for sharing or their own format for working on.

How can I upgrade Monterey 12.7.6 to MacOS 13?

You need a 2017 or later Mac.