Go to the website : office.com

Select the "Sign In" option

Type in your Microsoft user name in new prompt.

Hit "Next" and type in your password.

Select "Don't show this again" and select "Yes"

Hit "Next"

Select "I want to use a different authenticator app"

Click "Next"

A new prompt will appear with a QR code on it. (Like the one below)

Leave this open on your screen and swap to your mobile device.

Open the App store on your mobile device.

Search for the "Google Authenticator" app and download it.

Once the app has downloaded, open it, click through the screens until you see a screen similar to the one below.

Select to "Scan a QR code"

Allow the app permission to access your camera

Aim the green square that appears on your mobile device at the QR code still on your computer screen.

This will add a 6 digit code generator profile to the app.

Hit "Next"

Type in one of the 6 digit codes from the app into the new prompt

Hit "Next"

Your Microsoft Account is now protected by 2 Factor Authentication!