Every To Do item has a start date. By default, the start date is the date you created the item. The start date can be controlled whenever you edit an item by using the "Date to Start" controls:

Notice that "Today" is selected by default when you first create a new item. If you were editing an item that had previously been created, its start date would be the date of the original creation.

The start date of an item determines when it is listed. Use the status drop down menu in the show bar to control the display of To Do items:

If you choose Current, then all To Do items with a start date that matches today's date or is earlier than today's date are shown.

If you choose Future, only To Do items with start dates after today's date are shown.

If you choose Finished, then only items marked Finished are shown.