After you file

How to efile
https://ttlc.intuit.com/questions/1900599-how-do-i-e-file-my-personal-individual-tax-return

You will need your 2017 AGI.  How to find the AGI   https://ttlc.intuit.com/replies/3301618

If you already picked to mail it, How to change from Mail to Efile https://ttlc.intuit.com/replies/5561257