Change page template of Upcoming Events page

I am new to this plugin. The website I am working on, is using this plugin. I am having problem changing the template of the upcoming event page.
I have event categories page which lists all the event categories. But I am not able to create a custom template page for the events that is listed after visiting event category.
https://new2.thebridesofoklahoma.com/events/categories/open-house/

The page I need help with: [log in to see the link]