it is a lot simpler than all that... really:
Let's say user has 5 pictures and wants to rotate a new picture every 6 hours.
1.jpg through 5.jpg would be the pic names in this example.
upload all 5 pics to the same directory on the server, lets put them in the folder named "pics"
Step 1: add the php handler to your .htaccess to allow php scripts to be executed on HTML pages:
AddType application/x-httpd-php .html .htm
AddHandler application/x-httpd-php .html .php .htm
upload this .htaccess to your /root level directory.
Step2: open notepad and make a php page to handle all the pictures:
<?php
header("Content-Type: image/jpg");
$a = date('G');
if($a < 6) $file = "1.jpg";
else if($a < 12) $file = "2.jpg";
else if($a < 18) $file = "3.jpg";
else $file = "4.jpg";
readfile($file);
?>
save this as picture.php and upoad it with the picturtes them selves.
Now we have 5 pictures and a picture.php in the folder named "pics"
Step 3: Where ever you want your pictures to be shown add this line to the HTML page:
<img src= "http://yoursite.com/pics/picture.php">
That's it. You canadjust your picture.php to display 2, 3, 10 pictures at a time, and stretch it out to 12 hours, once a day, once a week, etc etc.
No need for a database with this one :D