Multiple vendor site – only allow them to see their own order when logged in?

hi all,
i am developing multi site using marketpress plugin
i want restrict order only allow them to see their own order when logged in?
My URL path
http://DomainName/wp-admin/edit.php?post_type=product&page=marketpress-orders

I found code and added in edit.php no result
$thisauthor=”;
if (!current_user_can(‘edit_others_posts’))
$thisauthor = ‘&author=’ . $user_ID;
wp(“what_to_show=posts&post_status_q&posts_per_page&=15&order=$order&orderby=$orderby” . $thisauthor);

please how to achieve this ?
thanks in advance