how do you randomise a image with php code insert

[oavs]

Hi

I have used this code successfully before provided by Nitro.
I now need to use the same code (because its so simple to add images later) for the following code. Following code is in the tpl_header.php.

<a href="<?=zen_href_link(FILENAME_SPECIALS)?>"><?=zen_image(DIR_WS_TEMPLATE.'image s/ban_2.jpg')?></a>


Code I have is -
<img src="includes/templates/gp_000/images/home/ban_<?php echo(rand(1,4));?>.jpg" width="408" height="239" />

So I have no idea how to implement this bit here to the above code in the tpl_header.php..-----
ban_<?php echo(rand(1,4));?>.jpg"


Can someone please help ?

Thanks in advance