Need help changing the background

I’m new to wordpress, and I can’t seem to figure out how to change the background on this theme. I have admin privileges, and I have access to the “customize” section on the toolbar. However, when I click on the tab for background image, it says that there is no background image selected. However, the page loads with a wood grain background. Another thing to note is the wood grain background image that loads doesn’t appear in my “media files”.

Anybody have an idea what’s going on here? I’d appreciate any help you could provide. Thanks!