Don't know if this helps you post a pic,but if you hit that button that says IMG,and then type in the info from your pic on Yahoo,it should come through.Just right click on the pic you want to post from Yahoo.When the box appears,hit "properties". There should be the http:// info you need to write in the post box.
If you have any pics saved in your computer files,you can transfer the to your own free page at http://freeservers.com Then you post them here from that site.Hope this helps. Also,for still pics,use jpg. For moving pics,use Gif.