Where is TurboTax asking you to provide values for lines 16 and 18? These are calculated values (like line 2 - line 1).
Do you have the CD/download software? Are you trying to plug numbers in the 2210 in Forms mode?
Annualizing is a method in which you try to check quarter by quarter if you had an underpayment of your taxes, in order to reduce your penalty.
If you are in Step-by-Step mode, what is the question that TurboTax is asking you?