On the WordPress Admin section how do I link to submenu pages created for a plugin?

admin_url() gets you the correct administration page URL (and network_admin_url() to get a network administration page URL)

Optionally, you can use add_query_arg() to append arguments to an URL, using an associative array:

$page="edit_record_page";
$rec_id     = 1;
$record_url = add_query_arg(compact('page', 'rec_id'), admin_url('admin.php'));