I am trying to find the ID of my posts page (the dynamic page that always displays the latest post on top). I found out that I need to include this code in index.php:
<?php $page_for_posts = get_option( 'page_for_posts' ); ?>
(I work with a child theme of TwentyEleven which has no home.php or front-page.php). I am a total beginner. Please could someone post a bit more code from index.php that makes it clear to me where the above snippet needs to be inserted? Is index.php even correct?