Look at the screenshot below. You want to click on the icon with the red arrow pointing at it, and you'll get a pop up screen where you paste the URL of whatever picture you want to post (to get this, right click on the picture and click on properties...you'll find it there). If the picture isn't online yet, you have to host it at a site like tinypic.com or xs.to You can't post something straight from your computer's hard drive. Hope that helps.
