How do I create custom event details that will appear on my event page?
This article will show you how to add a custom field you created in the custom field manager to your event page. For more on how to create a custom field check out this article.
You'll want to know the name of your custom field. You can find it here in the Custom Field Manager.

Go to your event in the Event Manager.
To learn how to create an event read more here.
Go to the bottom of the general tab and click on "Add a Custom Field Group.

Select the custom field you wish to display from the drop down menu.

Hit Save.