How do I create an overnight event

When creating a new event, click on the settings icon, top right of the creation screen.  This allows you to show extra fields.  Select the "Advanced" field, this will then appear as an option on the new event page.  You will need to use the Overnight option from the Advanced drop down list.  Then enter the start and end date and the times, for example 19th August to 20th August, Start 8.00 PM, End 10.00 AM.