If you e-filed you do not need to send in any documents, unless instructed to do so (for instance: you will need to send in your 1040-V payment voucher only).
You can
pay your Federal balance with your bank account for free, check or
choose an approved payment processor to pay by credit or debit card. You can
also setup payment installments.
Here's a link to the IRS website
for making
electronic payments: https://www.irs.gov/payments