O365 Two Factor Authentication basics

Users can change and modify their two factor authentication settings here

After enrolling into two factor authentication for O365, the user will see the following screen after logging into OWA:

If the user selects Send Me a Push it will send a push notification to their phone. Note that the user will need to be setup for push notifications. If the user selects Enter a Passcode they will be taken to a screen where they can enter the passcode they receive either from the Duo app or keyfob.

If the user has setup multiple devices, they can select it in the dropdown:

If the user selects Call Me then they will receive a phone call with the passcode they need to enter. The Enter a Passcode option is the same as the first example.