Featured image as header on /event/ page

Hello fine community!

I’m having a struggle with a site I’m working on. The issue is this:
The theme i’m currently using let me set the header for each page with a featured image. Since the “Event” page with the month calendar is self-generated this is never an option. Do anyone have a solution for this? Preferably a quick-fix. I’m not not that good in .php.

Here are some images to show you what I mean:
This is what i want to have:
Image 1

This is my problem:
Image 2

I’m using the theme “White Rock”.
In advance, thanks!

https://wordpress.org/plugins/the-events-calendar/