Have you already actually filed, or is your return still in preparation?
If you have not yet filed, does TurboTax think you were finished so the interview is closed, and you need to know how to open the return interview back up to edit entries?
If you just need to know how to open an unfiled return back up so you can finish it, click on "Add a State." That doesn't really add one, but opens the interview back up for an unfiled return.