If you selected "I will pay by bank debit", check with your bank account to make sure the money was actually withdrawn. If yes, send proof to the IRS. If no, you might have put a typo in the account number or the bank rejected the debit for some reason, and you owe the payment.
If you selected "I will pay by credit card" you were taken to a credit card company web site to put in your information. Check your credit card account. If no payment was made, you might have put a typo in the account number or the bank rejected the debit for some reason, and you owe the payment. If the payment was made, send proof to the IRS.
If you selected "I will pay on my own" then you need to make a payment. You can mail a check or make an electronic payment on the IRS web site at www.irs.gov/payments.
