Try this code:
<?php
$lastposts = get_posts('numberposts=1&category=1');
foreach($lastposts as $post) :
setup_postdata($post);
?>
<a href="<?php the_permalink(); ?>" id="post-<?php the_ID(); ?>"><?php the_title(); ?></a>
<?php the_content(); ?>
<?php endforeach; ?>
You can use other parameters to determine witch post you want to show like $offset
Have a look at that codex page for further reference
http://codex.wordpress.org/Template_Tags/get_posts
