Not sure what you are doing wrong, but here goes,
This is the link to the image you are trying to post
http://i62.tinypic.com/10olnap.jp g
When you want to post this image, hit the 'Insert Image' button in the reply box and paste this link
Voila!
Or you can manually type in the Image tag
[IMG]yourlink[/IM]G (The 'G' goes inside the bracket)
So it would look just like this
[IMG]http://i62.tinypic.com/10olnap.jp g[/IM]G (minus the spacing in the 'jpg' portion of your link and the 'G' in the closing tag would go inside the closing bracket).