Photoshop is an image editing program, photobucket is a free online image host.
As for your problem, I've found it.
http://img87.imageshack.us/i/picture844.png/ - This is what I was talking about when I said some users had problem with imageshack. When I said .png or .jpg I meant strictly that and nothing else, which means the / at the end of the URL is what is throwing it off. If you copy/paste that link into your browser you should be taken to the imageshack page. In the bottom right click "Link to share this image". Make sure you copy the direct link, and not the one that simply says "link". Copy and paste that url into image tags.
It should appear like this: