The best way is to post them at a photo sharing site like Photobucket or Flicker.
Then push the 3rd little button from the top left that looks like a little picture, when you hover over the button it says Insert Image. Push the button and [img][/img] comes up.
Put the URL of your picture between the ] and [
Now when you preview your post, the photo should show up.

I know it seems hard, but I've put up quite a few pictures here and this seems like the best way.