If you will not be paying the taxes owed by direct debit from your bank account, by mailing a check or by using a credit card, then select that you will be paying by mailing a check. File your tax return and do not mail a check. Go to the IRS payment website to pay the taxes owed either using Direct Pay or EFTPS - https://www.irs.gov/payments
...and note that EFTPS, or the IRS DirectPay sites, are only for paying taxes. They are not used for filing your yearly tax return forms themselves. Those final 2019 tax forms showing your yearly tax situation, must still be finished and filed.
IRS Direct Pay requires little information to set up, EFTPS is another story completely. you must enroll to use this form of payment.
here's a link to the IRS payments page which gives you the option to select from the many different ways to pay.
not that if this is for a 1040 the payment is late (was due 7/15/2020). regardless of which method you choose to pay, expect a notice from the IRS for late payment penalties and interest