You can only edit these options if you are an admin.

You can either code up an actual resource or you can paste raw HTML into home content of your event (an admin only ability)
If both are included, the raw HTML is placed above the resource file.
A separate file is preferred, and instructions for general event customization can be found at this page.

To use the event property, go to admin site --> Event --> Details --> set "HomeContent" field to be html of your choice