When you requested your extension you were supposed to pay your estimated tax due. Did you enter the payment you made into your tax return? Go to Federal>Deductions and Credits>Estimates and Other Taxes Paid>Other Income Taxes
If you prepared the extension in TurboTax, the amount of your payment should have been entered automatically. When you go to where xmasbaby0 told you to enter it, you might find that it is already entered there. Or check to see if it is on Schedule 3 line 8 on your tax return. If it was not entered automatically you will have to enter it.
If you need more help, please tell us whether you are using TurboTax Online or the CD/Download TurboTax software, and which edition (Basic, Deluxe, etc.).