Are you looking at the Info Wks? Part V is the bank info. Is one of the boxes checked for either direct deposit or direct debit? You said you need to pay federal tax? That would be a direct debit. Or see if you have Form 1040-V listed (further down in the Forms list) to pay a tax due by check.
Did you file yet? If you are not set up for direct debit from your bank account then you can pay i online at the IRS when you want. You can pay the IRS directly at
https://www.irs.gov/payments
