The date range picker allows you to look at audits from within a certain time period. By default, the date range is set from 7 days ago to the current time.
Clicking on the calendar icon will bring up the current dates month and year. You can select a day on this month, or you can go to a different month by using the back arrow which goes to the previous month, or the forward arrow which goes to the next month.
Alternatively, you can just enter the date manually by selecting in the text field and entering a date and time that follows the format dd/mm/YYYY h:mm.
For example, 12/23/2011 12:03 PM would be a valid date and time.