As long as you haven't actually filed yet, you navigate back to the section you want to edit.
The navigation selections are on the left side of the screen,.
After you get into your tax file, go to the left side of the screen and click on "Federal" , then make any sub-selections from there....first from the selections at the top of the screen.
Please spend some time navigating around to places you don't really want to go, until it become second nature as to how the navigation works.....don't just use the system's brain dead "Guide me" mode