CSS Drop Down Menu

I need to turn my category menu into a drop down menu. The layout before had it, but this new layout i have no clue how to do this. Ive googled and looked up websites on how to do it and nothing works just messes up my layout. Anyone think they can help? Here’s the code for the categories:

<?php $display_categories = array(10,394,15,955,13,4,14,16,6,5); $i = 1;
foreach ($display_categories as $category) { ?>

<div id=”cat-<?php echo $i; ?>” class=”category”>
<?php query_posts(“showposts=1&cat=$category”)?>
<span class=”cat_title”>”><?php single_cat_title(); ?></span>

“><?php echo category_description($category); ?>