Breadcrumbs, for those in need :)

Finally I've managed to do what I wanted(add breadrumbs). So, If you need to add breadcrumbs to marketpress, add this to functions.php of your theme. Then you must add <?php the_breadcrumb() ;?> where you want to place them, and style them using css.

function the_breadcrumb() {
	if (!is_home()) {
		echo '<a href="';
		echo get_option('home');
		echo '">';
		bloginfo('name');
		echo " » ";
		if (is_category() || is_single()) {
			$ID = $wp_query->post->ID;
			$categoria = mp_category_list($ID);
			echo $categoria;
			if (is_single()) {
				echo " » ";
				the_title();
			}
		} elseif (is_page()) {
			echo the_title();
		}
	}
}

I've added <?php the_breadcrumb() ;?> inside a div, like this
<div class="breadcrumbs"><?php the_breadcrumb(); ?></div>

and this is the css that I've used :

#content .breadcrumbs{
	width:100%;
	float:left;
	color:#E02D30;
	font-size:10px;
}
#content .breadcrumbs a{
	color:#E02D30;
}