If your images are showing up blank, 99.999% of the time it is because you pasted in the URL to the page (IMGUR, etc) that your image is found on, rather than the URL to the image itself.
You need to right-click on the image itself within that page, and select "Copy Image Address" from the drop-down. That's the URL we need. It will almost always end in ".JPEG" or ".JPG". If it doesn't end with a file extension, you almost certainly did something wrong.
A less common issue occurs when you attempt to paste an image URL for a private image. Please do not attempt to post images that reside in your Google Drive, or Apple Cloud, or any other protected location that obviously requires a password to access. Those images are not publicly available - which includes access to SBPS pages.
We have a help video for this!