To log in using two-factor authentication, you will enter in your username and password as normal.
After entering in your username and password, you will be presented with a screen to select your two-factor authentication option. Check the box Remember me for 30 days and select Send Me a Push.
You will see a confirmation that a push notice was sent to your device.
Your device will also show a notice on your lock screen that a request is waiting.
Open your Duo Mobile app, you will see a notice that your request is waiting. Press that notice to see the Approve/Deny options.
Select Approve if you are the person that is attempting the login. Select Deny if not.
Once the login is approved, the system will finish logging you in and you continue with your work.