All events can be edited by accessing them via your event type dashboard. Your event type dashboard is actually the window that you're redirected to immediately upon logging into your account. When you're on your event type dashboard, you'll be able to see all the events you've created.
Clicking on an event will allow you to access its settings. These are the same settings that you encountered when you first created an event. Making changes to these settings is how you update your event details.
These details can include things like the availability schedule your event references, the apps that the event can use, and the calendar where bookings for this event are located. It's a good idea after you make any changes to click the save button in the upper right-hand corner of the screen so that you don't lose any of your hard work.