You will not report this as income until next year on your 2019 tax return.
Sometimes TurboTax will change from year to year but here are the steps to follow in this year's program to get to the input screen for inputting a state refund:
1. Go to the Federal tab
2. Select Wages and Income
3. Go into Other Common Income
4. Start the Refunds Received for State/Local Tax Returns section.
5. Answer "yes" to "Did You Get a State or Local Tax Refund in 2018?"
6. Enter data here (be sure to note there is a drop down arrow to select the year)
