Hi Clark: It's fairly straightforward, actually.
First, the url link has to point to an image. Which means it should begin with http, and end with an image extension. Your link above ends in a forward slash, so it won't be an image, but an entire web page. If you enter the exact link in the address box of your browser, it should pull up the picture, and only the picture.
Of course, you need to determine the image's url using one of the usual methods - for example, by right-clicking it and loading it in a new window, or viewing its properties, or copying the image location, etc.
Second, simply surround the image url by img and /img tags in square brackest, fore and aft.
So in this case your link will look like this:
Code:
[img]http://img171.imageshack.us/img171/1992/mic.jpg[/img]
And produce this result:

Since you're using Image Shack, they make things easy for you. Just copy the "forum" code under "Embed this image", and paste that code into your post. VoilĂ .
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