How do I enter sale tax to amend my 2017 tax return using TurboTax online?

[taxq]

I am Washington state resident, when I filed tax return 2017 early of the year, I did not realize I can use sale tax in place of state tax. Because Washington state has no state tax, so I just left that blank.  I used TurboTax online preparing and filing the return.

Now I am using TurboTax online to amend the tax return 2017, but it is not clear to me how to do that. I come to "Income tax paid" section, but none of the items out there looks right.

Please help.

[HollyP]

First, you'll need to make sure you start the amended return by following the instructions located in this article. You'll know that you have begun the amended return when you see your refund/ balance due amount change to $0 in TurboTax. 

Next, follow the instructions in this article to enter your sales tax.