WordPress MU

Hi

I want to show in the home page of my blog only the titles of the post and just 3 lines. Is it possible? How can I do that?

Thanks

http://codex.wordpress.org/Template_Tags/the_excerpt

thank you.

I used : <?php the_excerpt(); ?>
It works for fy my home page,

however when I want to see the excerpt using the category or archive, I don't know where to put this code :

<?php if ( is_category() || is_archive() ) {
the_excerpt();
} else {
the_content();
} ?>