That's why I put "image.jpg" in the example. But yes you have to copy the link to the image itself (right click image > copy image link) and not just the link to the post that the image is on.
[ img ]
https://i.imgur.com/MHz493l.jpg[ /img ]
instead of...
[ img ]https://imgur.com/a/QH4yD4K[ /img ]
You don't have to make an account. An account is only required if you want to make public posts. Just uploading shit to link it somewhere else doesn't require you to log in.
https://media.tenor.com/XX7NGMX48RwA...rd-redford.gif