Changing Home Page Picture

http://www.andrewvasekmemorialscholarship.com. <– setting up a webpage for my cousins fundraiser.

I am trying to change the frontpage image that comes with Zerif Lite. I tried the featured image on the home page, but nothing changes. I made a copy of the home page, set the template to frontpage, saw the gray box where the original picture used to be, but cannot get the grey box to change to another image.

How do I changed the home page featured image?

Thanks!