Re:
Smartphones. Tablet, laptop...?
I would look at the image, in the pm.
Smartphones.....put finger on screen for a couple of seconds. An option to save image will appear. Click save image. It will be in your gallery/downloads.
Tablet, more or less the same....
Laptop/desktop...right click, choose save image, will end up in pictures/files.
Once image is in your chosen device, consider editing first, where you can crop image down to a smaller file size. This site has a low tolerance of big files.
Smartphones/tablet....even better, screen shot your image. It will auto save in a low resolution format. Less grief later on.
Then go through the usual faff with your build thread..add images now in your device, hopefully ready to be uploaded. Only takes a minute