Yehhhh got it working after a bit of hair pulling.
Rick Put me on the right track, and its a neat trick.

Thing to remember is you have to remember IMAGE
as that's what the css background-image is.

Your Style sheet calls the php script.
(Style Sheet Extra Properties)
.my_header {
background-color: none;
background-image: url('http://** Path to my Script**/image.inc.php');
background-repeat: no-repeat;
background-position: top center;
height: 104px;
width:695;
position: relative;
}

PHP FILE

<?php

##Source = Style Sheet Dark Grey.
# Exit must exist or it can cause problems.
# 1 file for the image and 1 file for the text wink

$today = date("dm"); // result == 2806 Day, Month

if ($today == ("0101")) {
header('Location: http://**Path to Seasonal Image/newyear/header-eve-dkblue.gif'); // Voila!
exit;
// Happy New year.
}
?>

You can then add more elseif to include more dates.

Ive read the the EXIT is important. So i would leave it there.

==============================================
Now in the Forum : Custom Inserts : Headers

Call the script to display the image in the div / class tag.
You can find more examples above wink

<table width="100%" border="0" >
<tr>
<td class="my_header"><div align="center"></div></td>
</tr>
</table>



Mines still in testing...
But seems to work fine, just need some headache tablets
as that battered my head at first but its simple now lol

This page my help
http://www.mambers.com/showpost-p_122103-postcount_23.html
or
http://www.mambers.com/showthread-t_24861-page_3.html


Phew was that complicated to get my head around lol


BOOM !! Version v7.6.1.1
People who inspire me Isaac ME Gizmo