After you file

No.  If your efile was rejected nothing got sent to the IRS.  You still need to pay.  Either with a check or directly only.  You can pay the IRS directly at

https://www.irs.gov/payments


But before you mail your return, why did it reject?  Maybe we can help you fix it.  If it was for the AGI then try entering 0 for the AGI and efile again.