Extra capability to wordpress user roles

I am trying to make editors(role editor) view users in wordpress. By default editor can not view users (list_user)

I searched different forums and found various codes but couldnot get desired result using any

$user = new WP_User( $user_id );
$user->add_cap( 'can_edit_posts' );

I am not able to figure out how to use these (where to put and how)

thanks