If you have the picture(s) on your computer go to
www.imageshack.us and then click on the tab marked "browse" Find the pic on your computer. Then click on "Host it"
Make a note of the codings it gives you. Especially the delete code as Imageshack is a FREE service so its not fair to block it all up IMO.
Then paste that URL into your message box. But put [img] before it and [/img] after it (no spaces)
Then click preview and it should all work