you can save the pic to your computer and then use the "attach file" option you see at the bottom of the "post reply" screen and it will just show as a link in your post (see below as i have attached a pic).
alternately, you can save the pic to an internet store (see one of the free pics sites that allows linking) and then use the "IMG" key you see in the "vB Code" section in the "post reply" screen and just insert the URL or path to the file whereever it is posted.
hope this helps. sorry i do not know of any free picture storage sites since i do hosting (free storage to me
). one of the other guys on here can point you to some though.