Retirement tax questions

STPickup... retirement fund.  I know it's taxable for state tax not federal.  my question is when I am entering the dollar amount in Turbo Tax for the STPickup, I entered it on the line next to STPickup then there is a drop down box with multiple choices.  Not sure if I have to pick one of those choices or just enter the amount on the line.  First choice is Maryland STPickup. There's no instructions that I find regarding the drop down box w/choices.