< img src="whatevertheURL" > You have to use the open and close brackets as well as quotes around the address (without spaces - I used them here so you could see the brackets). When you hit the Preview button, there will be your picture so you can see it before you hit the Post button.
< img src="http://news.yahoo.com/news?tmpl=story&u=/050826/480/txsw10208261844" >
Test
I did something wrong.
WARNING! Some websites object to people linking to their photos and some object to you using them at all, even if you copy and host them yourself.
Some websites will even substitute the picture you thought you linked to with a notice that you are stealing their bandwidth. Others have been known to substitute porn in place of the image you think you're linking to.
Best to host the pictures you are posting on your own website