Page auth with php am I doing wrong?

I'm creating a website with SESSION and I'm trying to make the index be viewed only by users, but even I'm login or logout my script still redirecting.

I created:

<?php 
if($_SESSION['id'] == true){
  break;
} else {
  header('Location:nologin.php');
}

?>

But when I do login, script still redirecting to nologin.php and I changed to:

<?php
if($_SESSION['id'] == false){
header('Location:nologin.php');
}
?>

And the problem still occurs, How do I do?