How to show posts from a specific author

I have this script that posts the date of and the 3 most recent blog posts from wordpress, but am wondering how I can modify it to only show posts from a certain author.

I've tried things like (have_posts('author=2')); etc... but not sure how it works???

<?php
/* site_last_updated
*
* This will check the modified_date of all published posts and give you the most recent date.
*
*/
function site_last_updated($d = '') {
$recent = new WP_Query("showposts=1&orderby=modified&post_status=publish");
if ( $recent->have_posts() ) {
while ( $recent->have_posts() ) {
$recent->the_post();
$last_update = get_the_modified_date($d);
}
echo $last_update;
}
else
echo 'No posts.';
}
?>

<?php while (have_posts()): the_post(); ?>
<?php endwhile; ?>
<span class="title">The Latest News</span><br/>
<span class="subtitle">Last Updated: <?php site_last_updated('') ?></span><br/><br/>
<?php while (have_posts()): the_post(); ?>
<span class="greensubtitle"><?php the_title(); ?></span>
<span class="bodytext"><?php the_excerpt(); ?></span>
<?php endwhile; ?>

 

let me know if this helps:
http://www.livexp.net/wordpress/how-to-list-wordpress-posts-by-author.html

It's not making use of the loop, which I believe can be done but I couldn't find out how on a quick search. The above will work though I believe.

$numposts = $wpdb->get_results("SELECT * FROM $wpdb->posts WHERE post_author = 1");
echo "Posts by Author 1";

foreach ($numposts as $numpost) {
echo $numpost->post_title."<br>";
echo apply_filters('the_content',  $numpost->post_content);
}

Code (markup):