There may be two alternatives. Go back to the Federal input area.
If you've started to post your Mortgage Interest (Form 1098), there is a space to enter your Real Estate Taxes there. These will carry over and be reported in the Real Estate Tax area.
I have also seen the situation where you try to enter the taxes under "Property Taxes" and there is nowhere to put the adjustment. If you go through the questions all the way to the end it will give you an opportunity.