Where do I input the four quarterly 1040-ES payments I have made?

Estimated taxes are entered under Deductions & Credits > Estimates and Other Taxes Paid. (Click the first screenshot below to enlarge it for reference.) 

To enter your 2016 estimated tax payments in TurboTax Online:

• Open (continue) your return in TurboTax Online. (If your return isn't open, you'll need to sign in and click Take me to my return.)
• Click My Account (top right of your screen).
• Select Tools.
• In the pop-up window, select Topic Search.
• In the search bar, type estimated.
• In the results box, highlight estimated tax paid, then click GO.
• You'll land on the Estimates and Other Income Taxes page. Click Start next to the applicable estimated tax payments you wish to enter (federal, state, or local). 
• Follow the onscreen instructions to enter your estimated payments. (Click the second screenshot below for an example.)