First off, create images of your authors and put them in a directory accessible to WP. Name the images the name of the author, i.e. my name is billh, so I’d make my pic billh.jpg.
Using the default Kubrick theme, open the file “index.php” in the your favorite text editor (do NOT use a word processor such as Word!).
Edit line #11. It looks like this in the original file:
<small><?php the_time('F jS, Y') ?> <!-- by <?php the_author() ?> --></small>
Change it to this:
<small><?php the_time('F js, Y') ?> <img width="40" height="40" src="pathtopics<?php the_author() ?>.jpg" alt="Posted by <?php the_author() ?>" /> </small>
You can change the values of “40” to anything you want, I just chose that as an arbitrary value. When you change themes, you’ll have to change where this kind of line appears.