Newbie help with replacing source theme image

I’m using “linked in 05” wordpress theme.
I don’t know a lot about editing in html for wordpress blogs (I understand regular html editing for non blog websites a bit). I’d like to remove a avatar thumbnail image on my homepage and replace it with another image. When I look at cpanel filemanager to find a file that I can change the image source, I can not locate a file. However, when I view source code in my browser of https://www.realestategranite.com, I see where I can change the image source in html. I just can’t find the file within my cpanel file manager to make the change. There are a dizzying amount of files for wordpress blogs :). Can you point me to the right file in my file manager?
Thanks in advance,