This video shows how to add multi-factor authentication (MFA) to a Microsoft 365 account. The video shows authentication being prompted automatically, but if you aren’t prompted, continue following the video to get to the My Account page from office.com, and you can add Authentication as an option from there.
Note: you will need a valid Microsoft 365 licence and a smartphone or tablet. Contact Tabard IT to check whether you have this, and help you get it if not.