How to use hooks to display info between header and posts

Hi I am trying to write a plugin that display information between the header and the 1st post. On my current template it would go:
<?php get_header(); ?>
[Information to go here]
<?php if (have_posts()) : ?>

<?php while (have_posts()) : the_post(); ?>

I have looked through the info at http://wphooks.flatearth.org, but can’t seem to find anything that covers. I was hoping for a pre_post filter hook. The sort of thing I am hoping to write is:

add_filter('pre_post', 'my_function');
function my_function($value){
echo $value;
return $value;
}
Iam new to writing plugins and am using this to help me understand better how WP works.
Thanks