The showcase header is the large image that is shown when you installed the template and seen it on every page.
Disable the Showcase Header for Your Own Image or Slideshow
This showcase header area is full width and can be used for a variety of media from static images to slideshows and even movie videos.
In your template parameters, you will need to disable this default demo image so that you can use your own media:
Now you are ready to add your own to the “showcase” module position.