After you file

https://sa.www4.irs.gov/secureaccess/ui/?TYPE=33554433&REALMOID=06-00008e4d-63f6-1187-a229-7c2b0ad00... 

click on the create ID.me account icon

To verify your identity with ID.me, you'll need to provide a photo of an identity document such as a driver's license, state ID, or passport. You'll also need to take a selfie or video chat with a smartphone or a computer with a webcam. If you need help verifying your identity or to submit a support ticket, you can visit the ID.me IRS Help Site .

 

take a selfie with your smartphone

and if you are using your computer rather than a smartphone to register you'll need to upload the selfie (face) to your computer 

or you can use your smartphone  to register

once on IRS website 

tap on - sign in to your online account

scroll down to the section that says id.me - create an account - and tap on it

follow the instructions from there