I am being asked to put an amount in Col-D State income, on Schedule IN-W. What is state income.

The software wants you to enter income taxable to Indiana.  For instance, if you are entering W-2 information, box 1 is $10,000 and box 16 is $2,000, you would likely enter the $2,000.

Indiana Schedule IN-W reports income and taxes withheld.

Indiana Instructions states:

If you have a withholding statement that withholds tax for multiple Indiana counties, enter the Indiana state income and Indiana state tax withheld once for that statement. Do not duplicate the Indiana state income and Indiana state tax withheld on multiple lines.

Instructions for the form may be found on page 35 of the Indiana 2023 IT-40 Full-Year Individual Income Tax Booklet.  See link on this page.