Am trying to efile just my 2018n federal return.i already paid Turbotax and i already submitted my bank info to pay my federal taxes due. very frustrated

What is happening?  Is it not transmitting or is your efile rejecting?   

Did you go through the File tab, through the 3 steps and hit the big orange Transmit Returns Now button?

You will need to enter your 2017 AGI to efile 2018.  If you didn't file a 2017 return or filed late in the year you enter 0 for the AGI.  If you are married and filed Joint last year you enter the same AGI for each of you.

When you efile you get back 2 emails.  The first email only confirms the transmission.  The second email says if the IRS (or state) Accepted or Rejected your efile.

How to Efile

https://ttlc.intuit.com/community/e-file/help/how-do-i-e-file-my-personal-individual-tax-return/00/25891