Cannot see summaries on the front page(just full text)

Hi,

This is my first post to this forum.
I am using WordPress 2.0 and i want to be able to diplay just summaries of articles on the front page, and not the full text. How do i do that. I went seraching through my admin panel everywhere but i couldn’t find it. Only thing that i found is to post summaries for syndication feeds.

Any help on this will be appreciated.
You can go to my site https://www.crankypot.com and see that it currently dispalys full text. Not summaries.

I wen through this forum and only thing i found to replace the_content with the_excerpt but my theme doesn’t have those lines.
Here is the index.php from my theme (black_letterhead)
<?php get_header(); ?>

<div id=”content” class=”narrowcolumn”>
<?php if (have_posts()) : ?>
<?php while (have_posts()) : the_post(); ?>
<?php require(‘post.php’); ?>
<?php endwhile; ?>

<div class=”navigation”>
<div class=”alignleft”><?php posts_nav_link(”,”,’« Previous Entries’) ?></div>
<div class=”alignright”><?php posts_nav_link(”,’Next Entries »’,”) ?></div>
</div>

<?php else : ?>

<h2 class=”center”>Not Found</h2>
<p class=”center”><?php _e(“Sorry, but you are looking for something that isn’t here.”); ?>
<?php include (TEMPLATEPATH . “/searchform.php”); ?>

<?php endif; ?>

</div>

<?php get_sidebar(); ?>

<?php get_footer(); ?>

Thanks in advance