As we say down here..."Chau" or is it "Chow"?
1. The image source must be on a server, not just your hard drive. Something like fotki or angelfire or your own home web page.
2. The format is:
< img src="http://www.pjcomix.com/images/shmoo1.gif" >
Remove the space after < and before >
3. Hot tip, if someone posts an image you like you can copy it by right clicking and selecting view page source. Copy the html gobbledegook to a text file, and trim off everything that isn't < img src= >, and use that as the reference to the image you want to copy. I keep my list on a running text file.
4. Hint, with a bit of practice, you can narrow it down more quickly by the post number, buried in the html.