bakercat:
Thank you for your reply. What exactly should I do? I have tried to edit it but I end up with my main page showing my main header and nothing else. I'm obviously doing something wrong but I'm not sure what.
That means you've got a coding error in there somewhere. PHP is pretty touchy. An extra carriage return, an apostrophe out of place, pretty much any small error will screw it up.
Here's a snippet from the file on one of my sites that I edited to change the menu:
<li class="submenu"><a href="<?php echo zen_href_link(FILENAME_DEFAULT); ?>"><?php echo HEADER_TITLE_INFORMATION; ?></a>
<ul class="level2">
<li>
<a href="index.php?main_page=page&id=4">About Us</a></li>
<?php if (DEFINE_SHIPPINGINFO_STATUS <= 1) { ?>
<li><a href="<?php echo zen_href_link(FILENAME_SHIPPING); ?>"><?php echo HEADER_TITLE_SHIPPING_INFO; ?></a></li>
The best way to learn is to try stuff. But, back it up first.