Add TinyMCE to textarea

What code can I use to add TinyMCE to multiple textareas on a page or to a single textarea for that matter.

This code adds some of the basic componets, but something more is needed to make it work? Does the textarea need a special id or class?

<?php
if ( user_can_richedit() )
	wp_enqueue_script('editor');
add_thickbox();
wp_enqueue_script('media-upload');
?>