Custom Field Background Image – Random

Hi all

well, i ha a cutom field called “background” where i inser images to display as background image. So far thats no problem. i an insert a image in that field in every page to show different background images.

now i want do show a random background image on startpage, or pages without a specific background-image, so i need 1st a if else, and then a random image from that custom field.

any idea for me???

her my code so far:

<?php ?>
<?php $image = get_post_meta($post->ID, 'background', true); ?>
<?php if (get_post_meta($post->ID, 'background', true) ) { ?>

<img src="<?php bloginfo('url'); ?>/wp-content/uploads/<?php echo $image; ?>" alt="<?php the_title(); ?>" title="<?php the_title(); ?>" />

<?php } else { ?>

HERE I NEED YOUR HELP!
i should show a random background image from that custom field.

<?php } ?>

Thank you very much!