How to change picture on main page of Salient WP theme

I told a friend of mine that it would be a five minute job to swap out the existing picture on her website main page with a new one. However, I can’t find where, in Salient, to remove the existing picture and insert the new one. I was expecting it to be a background picture but I couldn’t find where a background picture would be inserted into the theme. It is not embedded in the front page because the front page only contains text. It is in the framework somewhere, I just can’t figure out where. I have uploaded the new picture to the media library and I can see the old picture is there. To be clear, the picture I want to remove is of a family walking in the fall. I just can’t figure out where to go to make the switch. Can anyone help point me in the right direction?

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