Background color

Normally you would use the background-color property of the div. If you want it to extend the width of the page set the div width to 100% (or whatever width is relevant if you only want to cover a certain area) and then center your banner and menu.
Does that help?

Normally you would use the background-color property of the div. If you want it to extend the width of the page set the div width to 100% (or whatever width is relevant if you only want to cover a certain area) and then center your banner and menu.
Does that help?

I was thinking use some css i got the code of the banner and the menu:

<!--begin banner_slideshow-->
<center>
    <div id="slideshow">  
        <ul id="slide_fotos">  
            <li><img src="images/main_banner.jpg" alt="" title="Foto 01" />  
                <p></p></li>  
           <li><img src="images/banner1.jpg" alt="" title="Foto 02" />  
                <p></p></li>  
            <li><img src="images/banner2.jpg" alt="" title="Foto 03" />  
                <p></p></li>  
            <li><img src="images/banner3.jpg" alt="" title="Foto 04" /> 
				<p></p></li>  			
        </ul><!-- /fotos -->  
        <p id="pager">  
  
        </p><!-- /pager -->  
    </div><!-- /slideshow -->  
</center>
<!--end   banner_sslideshow-->

<style type="text/css">
.separador
{
	margin-right: 5px;
}
</style>

<!--begin menu_css-->
<div>
<ul class="menu">
	<li class="top"><a href="index.php" class="top_link"><span>Página Principal</span></a></li>
	<li class="top"><a href="inscricao.php" class="top_link"><span>Inscrições Online</span></a></li>
	<li class="top"><a href="cursos.php" class="top_link"><span>Cursos</span></a></li>
	<li class="top"><a href="contact.php" class="top_link"><span>Contacte-nos</span></a></li>
		
<?PHP
session_start();

if(is_logged())
{
?>
<li class="top"><a href="horarios.php" class="top_link"><span>Horários</span></a></li>
<li class="top"><a href="profile.php" class="top_link"><span>O Meu Perfil</span></a></li>
<?PHP
;}
?>
</ul>
</div>
<!--end  menu_css-->

background-color is a CSS property so I would add that to whatever styling rules you are applying to those areas.
Did you write this code or download it from somewhere? You have a style rule floating in the middle of the page.
And your PHP session_start() code needs to be the very first thing on the page to work i.e. right at the top, the first line of code. You can't have it further down the page like that - unless my PHP is very rusty...