second portfolio page

I try to create a second portfolio page in my website. All I did is to create a second portfolio template by duplicate the initial template-portfolio.php file and rename it. But in this portfolio page I want to show only the portfolio entries of one portfolio category . Can anyone help me with the query? I guess I have to change the code below

$args=array(
‘post_type’ => array (‘portfolio’),
‘orderby’ => $orderby,
‘order’ => ‘DESC’,
‘paged’ => $paged,
‘posts_per_page’ => $post_per_page,
‘ignore_sticky_posts’ => $do_not_show_stickies
);