Please help me find the best tutorial on how to change the header image to this theme? - grid focus by 5thirtyone. I appreciate any direction you are willing to/can provide.
I don't know the mentioned themes at all, so I will share with you a very simple solution. When you move the mouse pointer above the image, you may push the right button of the mouse. The short menu will offer you to display the image. If you click on it, only the image will be displayed, so you may grab the URL of the target object. If you need some extra information about the image you may want to save it into your desktop. When you have the new picture with the same height/width you need to upload it considering the URL of the image overwriting the already hosted one.