John I think you posted the thumbnail on accident. You are almost there
Just go to the big picture and copy the web address that shows up there (Highlight it right-click and select copy)
then paste it into your message body (right-click and select paste)
You can then highlight the web address and press the "Img" tag at the top. Don't make the mistake that I always make, check to see if there are any spaces between the address and the brackets.