scrollbar for posts

Hello, i want to be able to scroll the post only, not side bars, i have tried, i have this code, but when i insert new post overlays, i am using Simply Basic 1.5
this is in the main index.

<?php get_header(); ?>

<script language="JavaScript">
<!--
function MM_reloadPage(init) {  //reloads the window if Nav4 resized
  if (init==true) with (navigator) {if ((appName=="Netscape")&&(parseInt(appVersion)==4)) {
    document.MM_pgW=innerWidth; document.MM_pgH=innerHeight; onresize=MM_reloadPage; }}
  else if (innerWidth!=document.MM_pgW || innerHeight!=document.MM_pgH) location.reload();
}
MM_reloadPage(true);
// -->
</script>

<div id="Layer1" style="position:absolute; left:100px; top:108px; width:519px; height:550px; z-index:5; overflow: scroll">
<div id="main">

<div id="content">
<?php if (have_posts()) : ?>

			<?php while (have_posts()) : the_post(); ?>

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

					<h2><a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title(); ?>"><?php the_title(); ?></a></h2></div>
					<span class="date"><?php the_time('F jS, Y') ?><?php/* the_author() */?></span>

					<div class="entry">
						<?php the_content('Continue Reading &raquo;'); ?>
						<?php wp_link_pages(); ?>
					</div>

					<span class="metadata">
						Posted in <?php the_category(', ') ?> | <?php edit_post_link('Edit', '', ' | '); ?>  <?php comments_popup_link('No Comments »', '1 Comment »', '% Comments »'); ?>
					</span>

				</div>

			<?php endwhile; ?>

			<p><?php posts_nav_link(' - ','« Previous','Next »') ?></p>

		<?php else : ?>

			<h2>Not Found</h2>
			<p>Sorry, but the page you are looking for seems not to be here right now. Would you like to try again using the search feature?</p>
			<form method="get" id="searchform" action="<?php bloginfo('home'); ?>/">
			<form method="get" class="searchform" action="<?php bloginfo('home'); ?>/">
			<div><input type="text" value="<?php echo wp_specialchars($s, 1); ?>" name="s" class="search_input" />
			<input type="submit" class="searchsubmit" value="Search" />
			</div>
			</form>	

		<?php endif; ?>

		</div>

<?php get_sidebar(); ?>

	</div>

<?php get_footer(); ?>