To complete Step 6 State taxes, sub-step Living in the US you have to report where you have been during the tax year from January 1st to the end of December. Please note that after you add an exit date, a new row will pop-up. If you have been outside of the US, you will see "Outside US" displayed on the newly-populated row.
Important: Please note that Step 6 Living in the US perfectly reflects the US visits that you have reported on Step 1 Residency status. In case you think that the information on Step 6 is incorrect, please go back to Step 1 and double-check the US entries that you have added.