The "Preferred Choice" entry field gives you two options: Mt. Whitney Trail Overnight Permit, and DAY USE of Mt. Whitney Zone.
Both those permits are for starting at Whitney Portal. There are no other trail head starting points available in the lottery. Whitney Portal is the only starting point in the lottery.
The link provided by JimC takes you to the available dates page, and if you click the "Apply Now" button, it takes you to the page I referred to, with the "Preferred Choice" field.
