Rewrite rules for custom post type

You need to look at add_rewrite_tag() and add_rewrite_rule()

Also read this and this topics. They are very close to you issue.

After you setup rewrite rule don’t forget to flush rules

add_action( 'wp_loaded','my_flush_rules' ); // flush_rules() if our rules are not yet included
function my_flush_rules(){
    $rules = get_option( 'rewrite_rules' );
    $pattern = 'news/([^/]+)?'; // the same pattern that was used in add_rewrite_rule
    if ( !isset( $rules[$pattern] ) ) {
        global $wp_rewrite;
        $wp_rewrite->flush_rules();
    }
}