Customizing the dashboard page or post overview

Question

What would be the best way to add some basic HTML to the page overview (edit.php)? Basically I want to add some text, like a meta box, to explain some things about the page system to my multisite users.

Found the answer thanks to the solution provided by OleVik. Here's a few more resources on the topic:

How to show an urgent message in the WordPress admin area Plugin API/Action Reference/admin notices

Answer 1

I use a version of the following, to add text to the top of the Page (edit.php?post_type=page):

// Show message when viewing pages
function page_AdminMessage()
{
    showMessage("You are now viewing the Pages", false);
}
if ($_GET['post_type'] == 'page') {
    add_action('admin_notices', 'page_AdminMessage');
}

Which just needs to be added into functions.php.