Add bar that is not a part of container

Hi guys,

I have pretty much no experience with css and i was wondering if somebody can help me with my task. I am trying to add a commercial bar that is outside the container. I edited CSS by adding

#advertisment {
float:right;
position:fixed;
top:200px;
}

Now I don't where should I add the code to my html. Should I edit index.php by adding
<div id="advertisement">
<a href="http://www.aukro.cz/?ap=1&amp;aid=7894813&amp;bid=69413"><img src="http://www.aukro.cz/ap/ap_show.php?aid=7894813&amp;bid=69413" width="120" height="600" alt="Aukro.cz" title="Aukro.cz" style="border:none;" /></a>
</div>


but where should I put the code?

here is my index.php file:

<?php get_header(); ?>

<div id="post-entry">

<?php $postcount = 1; ?>

<?php if (have_posts()) : ?>

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

<div class="post-meta" id="post-<?php the_ID(); ?>">
<div class="top-meta">
<div class="post-title">
<h1><a href="<?php the_permalink() ?>" rel="bookmark" title="<?php the_title(); ?>"><?php the_title(); ?></a></h1>

<div class="post-author"><?php _e('Publikoval'); ?>&nbsp;<?php the_author_posts_link(); ?> v <?php the_time('l, j F Y') ?>&nbsp;&nbsp;&nbsp;<?php edit_post_link('upravit'); ?>


<?php include (TEMPLATEPATH . '/submit.php'); ?>

<?php include (TEMPLATEPATH . '/ratings.php'); ?>

</div>
</div>

<div class="calendar"><?php the_time('j'); ?><br /><span class="c-month"><?php the_time('M'); ?></span></div>
</div>

<div class="post-content">
<?php the_content('...pro více klikněte zde'); ?>

<?php if($postcount < 4): ?>

<!--[if !IE]> if you want to used your own google tracking code. just replace the code inside the p tag<![endif]-->

<p>
<script type="text/javascript">
google_ad_client = "<?php include (TEMPLATEPATH . '/adsense-config.php'); ?>";
google_ad_width = 468;
google_ad_height = 60;
google_ad_format = "468x60_as";
google_ad_type = "text_image";
google_ad_channel = "";
google_color_border = "FFFFFF";
google_color_bg = "FFFFFF";
google_color_link = "003366";
google_color_text = "565656";
google_color_url = "666666";
</script>
<script type="text/javascript"
src="http://pagead2.googlesyndication.com/pagead/show_ads.js">
</script>
</p>

<!--[if !IE]> end if 3 loop in post <![endif]-->

<?php endif; ?>

</div>


<?php include (TEMPLATEPATH . '/social.php'); ?>

</div>

<?php $postcount++; ?>

<?php endwhile; ?>

<?php include (TEMPLATEPATH . '/paginate.php'); ?>

<?php else: ?>

<?php include (TEMPLATEPATH . '/result.php'); ?>

<?php endif; ?>

</div>

<?php get_sidebar(); ?>

<?php get_footer(); ?>

=================================
=================================

here is the beginning of my CSS file:

/*

Theme Name: LightBreaker
Theme Style: Unique Dark WordPress Theme
Theme URI: http://www.wpthemesplugin.com
Description: 3 column seo optimized custom wordpress theme with tab and advertisment slot
Author: Moses Francis
Author URI: http://wpthemesplugin.com

Copyright 2007-2008 wpthemesplugin.com

*/

body {
font-family: Verdana, Arial, "Times New Roman", sans-serif;
font-size: 65.7%;
color: #565656;
margin: 0px;
padding: 0px;
background: #323232 url(images/background.gif) repeat-x top;
}
h1, h2, h3, h4, h5, h6 {
font-family: Georgia, Geneva, Verdana;
font-weight: normal;
}

#light-wrap {
margin: 0px auto;
width: 1160px;
float:left;
}
#advertisement {
float:right;
position:fixed;
top:200px;
}
#light-container {
margin: 0px;
width: 960px;
float: left;
}
#light-header {
margin: 0px;
width: 960px;
float: left;
padding-top: 30px;
padding-bottom: 10px;
}
=======================
=======================

Thanks a lot for your help!
Kuba