Use the Dates and Times screen under the Event tab to add and remove days and edit the start and end time of each day.

To add another day to your conference click the "Add Day" button and select the date you wish to add from the drop-down calendar.

Note: You cannot remove an event day if there are sessions scheduled on that day or if there are no other event days.

To adjust the time of either the beginning or the end of the day hover your cursor over the small dot and then drag it to your desired time.