Go to your imgur account and upload the image you want to display to an album - make a note of the file extension - whether it's png, jpg, etc.   Go to the image and click on the "copy" button next to the link:   Now go back to your forum post and click on the "Insert Other Media" and choose insert Image from URL"   This brings up the following window:   Paste the Copied URL into this box but do not click on "Insert into post" yet - the URL is not