You would enter this in Deductions and Credits in the Federal Taxes section. If you don't see the option that says Car Registration Fees in the list of "Your tax breaks" (this comes from the boxes you selected when you first started), then you can click the blue link that says, "Check for tax breaks" and then, "Jump to Full List". You will see an option that says Cars and Other Things You Own. The Car Registration Fees will be there.

Please let me know if you have any other questions.