I think the image has to be placed somewhere on the web, then when the poster "places" the image in the post what is actually a pointer to that web address is placed in the posting. Final result is that it appears as if the image is in the post.
The one thing I kow for sure is that if you try to insert an image that is on your computer and not also available through the web, nothing will show in the post.
I have found if you load a picture under photos on the top forum tool bar. You can later go in and make a short comment about it, and the photo will then appear in the Lake Martin Fopics section. At least, it worked once for me.
On the image, I right clicked "copy". Then I came here, set my cursor on the message part of the post and right clicked "paste". I didn't have to use an image code or tie it to the URL, like I would if it was an article or a photograph.
For some reason, this particular comic struck me as so funny this morning, I just wanted to share it with you all.