Here's an alternate navigation method if you have any trouble with the above.
With your return open, at the top right click on SEARCH.
Enter the term 1040-ES without quotes, and click the blue magnifying glass.
Then click "Jump to 1040-ES."
Next screen says: "Adjust how much tax you pay." It first asks if you want to change your W-4 withholdings (if applicable). Yes or no.
If "yes", it will first have screens about your W-4.
If "no", the next screen will be "Estimated Taxes for 2019" which asks if you want to prepare estimated taxes.
