Right click on your picture, and you should see the property of the file in HTTP URL format, do a copy.
Then to have your picture show up here, just use the IMG tag before and after the URL that you copied. Do not put the period, I used it to show you the format. Also, no spaces between the URL and the tag itself.
EX: [I.M.G]http://pictureURL[/I.M.G]
like this:
[img]http://www.imagestation.com/picture/sraid95/p54fc0e71354db76962d594be18531326/fa322d67.jpg