filtering posts

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

                                <?php

                                    $custom = get_post_custom($post->ID);

                                    $large_image_url = wp_get_attachment_image_src( get_post_thumbnail_id(), 'large'); 

                                    $cat = get_the_category($post->ID); 

                                ?>

                                <?php $cur_terms = get_the_terms( $post->ID, 'portfolio-category'); 

										foreach($cur_terms as $cur_term){  

									};

									$catt = get_the_terms( $post->ID, 'portfolio-category');

									$slugg = ''; 

									foreach($catt  as $vallue=>$key){

										$slugg .= strtolower($key->slug) . "";

									}

								?>

                                    <div class="span4 portfolio_item block <?php echo $slugg; ?> "data-filter="">

                                        <div class="view view-first <?php if ($oi_data['portfolio_image_hover_icons'] == "Zoom icon only") { ?>nolink <?php } ?> <?php if ($oi_data['portfolio_image_hover_icons'] == "Link icon only") { ?>noinfo <?php } ?>">

                                            <a href="<?php echo $large_image_url[0]; ?>" rel="prettyPhoto"><img src="<?php echo $large_image_url[0]; ?>" alt="" /></a>

                                            <div class="mask">

                                                <?php if ($oi_data['portfolio_image_hover_icons'] == "Zoom icon + Link icon") { ?>

                                                <a href="<?php echo $large_image_url[0]; ?>" rel="prettyPhoto" title="<?php the_title(); ?>" class="info"></a>

                                                <a href="<?php echo get_permalink(); ?>" class="link"></a>

                                                <?php } ?>

                                                <?php if ($oi_data['portfolio_image_hover_icons'] == "Zoom icon only") { ?>

                                                <a href="<?php echo $large_image_url[0]; ?>" rel="prettyPhoto" title="<?php the_title(); ?>" class="info"></a>

                                                <?php } ?>

                                                <?php if ($oi_data['portfolio_image_hover_icons'] == "Link icon only") { ?>

                                                <a href="<?php echo get_permalink(); ?>" class="link"></a>

                                                <?php } ?>

these codes display all the portfolios in a single page. I have 3 sample portfolios with different category each. What i want to achieve is to show only the portfolio of a certain category. What should i do? I’m not familiar with functions like get_post_custom…etc.