To attach a screen shot, any photo, it has to be on the web, not on your computer.
There may be easier ways, this is what I figured out:
I make a new virtual system, i.e. dads floor plan, import the screen saver (jpeg) to the virtual system. that gets it on the web.
right click the photo and copy image address (not the photo)
next, in your post: using the photo icon top bar (6th from left), paste the image address (url)
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after that, you can delete the virtual system if you want.