If it didn't transfer over from last year then enter a refund from last year that you applied to this year here. BUT first make sure it's not already there. You don't want to apply it twice.
Deductions and Credits
Then scroll way down to Estimates and Other Taxes Paid
Income Taxes Paid - Click the Start or Update button
Next page scroll down to 2019 Refund Applied to 2020
Click Start or Update by the tax you applied
By the way, a state refund applied to the next year can be a federal itemized deduction if you have enough deductions to itemize. And even though you applied a state refund to the next year or it went to back taxes or something, you still have to claim it as income on your federal income tax. It was still for your benefit. You still got it you just did something with it. A State Tax Refund is taxable if you itemized deductions on that prior year's federal return and took a deduction for state income taxes instead of the sale tax. You got a deduction benefit for it so now you have to include it as income. If you took the standard deduction it is not taxable and you don't need to report it.