how to retrieve first image as thumb - wordpress

how to retrieve first image as thumb from the post in wordpress.

now im using the code, which is successfully work, but the thumb will be crop not resize. can anyone tell me how can resize thumb not crop by modification the code.

i add this code in funtion.php

// Retrieve the src of first image in a post
function bm_extract_string($start, $end, $original) {
$original = stristr($original, $start);
$trimmed = stristr($original, $end);
return substr($original, strlen($start), -strlen($trimmed));
}
function getFirstImage() {
$content = get_the_content();
$pic_string = bm_extract_string('src="','" ',$content);
$imagesize = getimagesize($pic_string);
list($width, $height, $type, $attr) = getimagesize($pic_string);
$link = get_permalink();
$title = get_the_title($post->post_title);
echo '<a href="'.$link.'" style="background:url('.$pic_string.'); display:block; width:100px; height:150px;" title="'.$title.'"></a>';
}

Code (markup):

and than this code in the template like - search result, archive, index etc

 

i not really know how to solve your problem.
But, i have been use this scirpt to resize image

<?php $postimageurl = get_post_meta($post->ID, 'post-img', true); if ($postimageurl) { ?>
                    <div class="pic fl">
                      <a href="<?php the_permalink(); ?>" rel="bookmark" title="Permanent Link to <?php the_title_attribute(); ?>"><img src="<?php echo $postimageurl; ?>" alt="Post Pic" width="200" height="200" /></a>
                    </div>
					<?php } ?>
					<div class="post-title">
						<h2><a href="<?php the_permalink(); ?>" rel="bookmark" title="Permanent Link to <?php the_title_attribute(); ?>"><?php the_title(); ?></a></h2>
					</div>

Code (markup):

Example:
_http://wptheme.dankerizer.net

 

where i use this script

 

you can put that script AFRTER this scipt :

	<div class="box post" id="post-<?php the_ID(); ?>">
				<div class="content">

Code (markup):

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