T3RCZ on "Showing the whole last post on homepage"

First of all, I'd like to apologize, my experience with php is very, very basic.

I edited the code as following:

<?php
global $query_string; $more = -1;
query_posts( $query_string . '&posts_per_page=1' );
?>

But nothing happened. Woudln't you mind to show me how to use this? Im sorry to bother you, I'm just not sure how this works. :(