If you have not submitted your tax return yet, just click on the "federal" tab on the left hand side of the screen, "deductions and credits" on the top of the screen and "show more" next to "your home." From there you will see the real estate tax option.
If you have submitted your tax return, you will have to wait and see if the return is accepted or rejected. If rejected, you will have to make the changes needed for the return to be accepted. There will be a notice explaining what the rejection reason was. In addition, you will also get the opportunity to make the change to the real estate tax amount.
However, if the return gets accepted you will have to wait until you receive your refund prior to amending your tax return. When the turbo tax program is updated later in the season, you will be able to log back into turbo tax and amend the return, adding whatever you have omitted.
To amend the return using Turbo tax, just log back into your account, open the return that you have filed and from there you will see the tab for amending your return. Here is a link that can help further guide you when you are ready to amend. How to amend your tax return
