Help Drop-down Menu

Does anyone have any idea what I should do to switch my current menu to a drop-down menu?

This is its CSS style:

#navigation ul li a:link, #navigation ul li a:active, #navigation ul li a:visited {
	margin:0; padding:13px 15px;
	font:bold 1.08em Arial, Helvetica, sans-serif; color:#34393e;
	display:block;
}

#navigation ul li a:hover {
	color:#000;
	font-weight:bold; text-decoration:underline;
}

#navigation ul.pages li.current_page_item a:link, #navigation ul.pages li.current_page_item a:active, #navigation ul.pages li.current_page_item a:visited {
	/* Crazy margins to pull up the hover image above the borders.*/
	margin:-3px 0 0 0; padding:15px 15px 14px 15px;
	background:#171615 url(images/navigation-hover.gif) repeat-x bottom center;
	color:#f1f8ff; position:relative
}

How do I make it dropdown?