Show Post of a single Category per Blogpage

Hi everybody,

I am not an expert on wordpress. I will describe what I would like to do and maybe someone can tell me it is possible or not and if it is how I can do it.

I would like to show Post from a single category on my blog. To do this I would like the modify the template for the blog. Then I would like to copy that template, change the name and the category so that i can select different templates for pages.

Here is the code for the template:

<?php /* Template Name: Blog */

get_header();
$catid = get_query_var('cat');
$cat = &get_category($catid);

$custom =  get_post_custom($post->ID);
$layout = isset ($custom['_page_layout']) ? $custom['_page_layout'][0] : '1';
$promo = get_post_meta($post->ID, "_promo", $single = false);
$slider = get_post_meta($post->ID, "_chosen_slider", $single = false);
$al_options = get_option('al_general_settings');
$breadcrumbs = $al_options['al_show_breadcrumbs'];
$titles = $al_options['al_show_page_titles'];
?>
<div class="container region3wrap">
	<?php if(!empty($slider[0]) ):?>
		<div class="mainslider-container responsive">
		<?php putRevSlider($slider[0]); ?>
		</div>
	<?php endif?>
	<?php if(!empty($promo[0]) ):?>
		<div class="row content_top promo-block">
			<div class="twelve columns">
				<h2><?php echo do_shortcode($promo[0]);?></h2>
			</div>
		</div>
	<?php endif ?>
	<?php if($breadcrumbs):?>
		<div class="row content_top">
			<div class="nine columns">
				<?php if(class_exists('the_breadcrumb')){ $albc = new the_breadcrumb; } ?>
			</div>
			<div class="three columns">
				<div class="row">
					<div class="twelve columns">
						<?php get_search_form(); ?>
					</div>
				</div>
			</div>
		</div>
	<?php endif ?>
</div>

<div class="container region4wrap">
  	<div class="row maincontent">
		<?php if ($titles == 1):?>
			<div class="twelve columns">
				<div class="page_title">
					<div class="row">
						<div class="twelve columns">
							<h1>
								<?php
									$headline = get_post_meta($post->ID, "_headline", $single = false);
									if(!empty($headline[0]) ){echo $headline[0];}
									else{echo get_the_title();}
								?>
							</h1>
						</div>
					</div>
				</div>
			</div>
        <?php endif?>
		<?php if ($layout == '3'):?>
			<div class="four columns sidebar-left"> <?php if ( !function_exists('dynamic_sidebar') || !dynamic_sidebar("Blog Sidebar") ) : ?> <?php   endif;?></div>
		<?php endif?>
 		<div class="<?php echo $layout == '1' ? 'twelve' : 'eight'?> columns">
			<?php
                $temp = $wp_query;
                $wp_query= null;
                $wp_query = new WP_Query();
                $pp = get_option('posts_per_page');
                $wp_query->query('posts_per_page='.$pp.'&paged='.$paged);
                get_template_part( 'loop', 'index' );
            ?>
    	</div>
       	<?php if ($layout == '2'):?>
			<div class="four columns sidebar-right"> <?php if ( !function_exists('dynamic_sidebar') || !dynamic_sidebar("Blog Sidebar") ) : ?> <?php   endif;?></div>
		<?php endif?>
        <div class="clear"></div>
	</div>
</div>
<?php get_footer();?>