For folks struggling, one of the easiest ways to post from a webpage (not usually a photo hosting site such as imgur, which is mentioned below) is to right click on the image, if using Chrome, and click ‘open image in new tab’
The address bar in that new tab will have the URL which begins hhttp or https: etc, but importantly will end with “.gif”
Copy that, paste it in here and job jobbed.
For photo-hosting sites, look at all the various options it gives you and pick the only one that will end “.gif”
This also works for photos, which will end “.jpg” ” or “.bmp” etc – basically if it doesn’t brutally end with a “.xyz” it’s not the one you want.
I think that’s the simplest way of putting it, but others feel free to chip in 🙂