Failed to load image

I watched the demo carefully and at one point in the demo an image is loaded and then previewed. However, when I load an image, there is no preview, nor does the image show up on my blog page, even though I followed the same steps, including “save” (and the image is a jpeg less than 1 meg).
At this point, all I have on my blog page is the ad space holder.
Any suggestions?

https://wordpress.org/plugins/ad-widget/