While checking state taxes, the indiana withholding statement is requesting a Col C-FeD ID Number. Not sure what this is or where to locate it.

This is the Employer/Payer ID Number.  You should be able to locate it on your W2 or 1099 form.  TurboTax uses the W2 Box 15 number, but if it is blank you may have to enter the one in the Payer Information section (b).