I'd like to have a header on the comment list. Is there a php if statement that I could use? Something like <php if $first : ?>. I can't find it.
You can override comment-wrapper.tpl.php. Find the comment-wrapper.tpl.php from your current theme and make a copy of it in your development directory. From there you can modify it to add your header. As an illustration see below (but you need to use the comment-wrapper from your current theme).
<?php
// $Id: comment-wrapper.tpl.php,v 1.2 2007/08/07 08:39:35 goba Exp $
/**
* @file comment-wrapper.tpl.php
* Default theme implementation to wrap comments.
*
* Available variables:
* - $content: All comments for a given page. Also contains sorting controls
* and comment forms if the site is configured for it.
*
* The following variables are provided for contextual information.
* - $node: Node object the comments are attached to.
* The constants below the variables show the possible values and should be
* used for comparison.
* - $display_mode
* - COMMENT_MODE_FLAT_COLLAPSED
* - COMMENT_MODE_FLAT_EXPANDED
* - COMMENT_MODE_THREADED_COLLAPSED
* - COMMENT_MODE_THREADED_EXPANDED
* - $display_order
* - COMMENT_ORDER_NEWEST_FIRST
* - COMMENT_ORDER_OLDEST_FIRST
* - $comment_controls_state
* - COMMENT_CONTROLS_ABOVE
* - COMMENT_CONTROLS_BELOW
* - COMMENT_CONTROLS_ABOVE_BELOW
* - COMMENT_CONTROLS_HIDDEN
*
* @see template_preprocess_comment_wrapper()
* @see theme_comment_wrapper()
*/
?>
<div id="comments">
<h2>My Comment Header</h2>
<?php print $content; ?>
</div>