You can post the pictures to an image-sharing website (photobucket works best for this forum, for whatever reason).
Then when you post the reply, do you see those buttons under the title box? Click the one that says "image", and you'll get this:
[image][/image]
Copy and paste a link that leads directly to said image (they usually have .jpg at the very end), in between the "[image]" and the "[/image]".
How you get the direct link depends on what website you post it to, though in photobucket, there are "share links" at the side of the image, that you can copy, and you would want to use the "direct" link.
So it should look something like this: (minus the spaces)
[image]
http://i49.photobucket.com/albums/f286/ ... wgpbxv.jpg [/image]
And you'll know you've done right when the picture actually shows.