In order to see the pic you posted here, users need to register on the other site, and have it setup to automatically log them in when they visit that site. The way you can tell is if in the post, the image is an attached pic. It usually says so right above the first pic. This is what non-registered users see when they click on the link. You can see where it says Attached Images.
If you want to post pics here, you need to use a pic hosting service like photobucket.com, flickr.com, webshots.com, etc. Create an account and upload images to those sites. Then those sites will provide you with a image linking URL for each image. They use the [img] tags that are supported on this forum.
[img]url[/img]
If you quote this message, you will see the URL with the IMG tags for the pic above. I use photobucket for my image hosting.