This is a screen-grab of the Blogger Template Designer.
I wanted to add a background image to this blog, which is easy to do. Just click on 'Background' and then click on the template you are using and that will bring up options to choose a background that is sitting in Google's repository, or to upload your own image.
I uploaded an image that was a plain color overall except for the printed words down the left side. I made the image and uploaded it.
Where were the words? I couldn't see them.
That's when I noticed something I had not noticed before.
See the little white square within the larger outline of a square? Mine was set with the white square at top middle. So the design was hidden behind the content.
I clicked to move the white square to top left and - Bingo!