If you need to record hours for a previous day, click on the calendar icon (to the right of "mm/dd/yyyy") in the "Specify date" box. You should see a date selection tool appear. If so, select the day when you worked. You may need to use the navigation arrows to select the previous month. After entering the day, proceed to enter your hours as before and submit your entry.

Note that some browsers on some devices do not provide a date selection tool. In tat case, you will have to manually enter the date.