get_the_content( $more_link_text, $stripteaser )
get_the_content does not take a post ID as a parameter, it always refers to the current post.
Also, don’t use magic numbers or hardcode post IDs into your theme, it will break after an import/export or migration.
Instead use get_page_by_title, which is not as bad:
// get the post
$post = get_page_by_title('page or post title', OBJECT, 'post' );
// filter its content
$content = apply_filter('the_content', $post->post_content );
// display it
echo $content;