You are using the link straight to the page where your photo is. That won't work. Follow these instructions to get the correct link.HOW TO
Now, if you scroll down past this post, there is a "Quick Reply" box. Below that, 3 red boxes. Click the one on the right that says "Use Full Editor".
You can now see all of your options. The one to the right of the smiley, that looks like a picture of mountains and sky, click it. (Hint: You can see what each of these does by hovering your cursor over them for a moment).
A small dialog box will pop up. http:// is auto-populated, and highlighted in blue. RIGHT click right on top of that highlighting, and insert the code you pasted above. Then at the bottom of the page, click Post Reply.