Change my Blog Logo in Browser Tab

Hello! I’m running the latest wordpress version with a child theme on Twenty Twelve on my site: https://www.jkhnelson.com. I’d like to change the black box that shows up in the browser tab to some other kind of logo or image (similar to every other website, including this one).

I do not have advanced CSS running, I can’t seem to figure out how to turn that on. What are my other options for changing this logo? I can’t find the file in my control panel to just swap out the image.

Thanks!