Hi there,
simplest method is to use the WordPress Custom Fields, create your field and add the data you want to display and then add this to the hook changing Your-Custom-Field
to your field name.
<?php
global $wp_query;
$postid = $wp_query->post->ID;
echo get_post_meta($postid, 'Your-Custom-Field', true);
wp_reset_query();
?>
You can also do this in Page Headers, same process of creating the custom field but then simply add this template tag:
{{custom_field.name}}
The name being the name of the field