How can I change my navigation from horizontal to vertical?

HTML Code:
<ul id="menu">

<!-- Start of Home-->

  <li><a href="#">Home</a></li>
    
  
  <!-- End of Home-->

  <!-- Start of North America-->

  <li><a href="#">North America</a>
    <div class="menu-container-4">
      
      <div class="column-1">
        
        <ul>
          <li><a href="#">Canada</a></li>
          <li><a href="#">United States</a></li>
        </ul>
      </div>
      <div class="column-1">
        
        <ul>
          <li><a href="#">Cuba</a></li>
        </ul>
      </div>
      <div class="column-1">
        
        <ul>
          <li><a href="#">Mexico</a></li>
        </ul>
      </div>
      <div class="column-1">
        
        <ul>
          <li><a href="#">Suriname</a></li>
        </ul>
      </div>
    </div>
  </li>
  
  <!-- End of North America-->

  <!--Start of Central America-->

  <li><a href="#">Central America</a>
    <div class="menu-container-4">
      
      <div class="column-1">
        
        <ul>
          <li><a href="#">Canada</a></li>
          <li><a href="#">United States</a></li>
        </ul>
      </div>
      <div class="column-1">
        
        <ul>
          <li><a href="#">Cuba</a></li>
        </ul>
      </div>
      <div class="column-1">
        
        <ul>
          <li><a href="#">Mexico</a></li>
        </ul>
      </div>
      <div class="column-1">
        
        <ul>
          <li><a href="#">Suriname</a></li>
        </ul>
      </div>
    </div>
  </li>
  
    <!--End of Central America-->

Code:
body {
	font-family:Helvetica, verdana, arial, sans-serif;
}
#menu ul, #menu li {
	line-height:22px;
	text-align:left;
	font-size:14px;
}
/* menu starts here */

#menu {
	list-style:none;
	width:940px;
	margin:0 auto;
	height:45px;
	padding:5px 30px;
	/* rounded corners for different browser support */
    
    border-radius:5px 5px 0 0;
	-moz-border-radius:5px 5px 0 0;
	-webkit-border-radius:5px 5px 0 0;
	/* css3 gradient */
    background:#333333;
	background: -moz-linear-gradient(#444444, #111111) repeat scroll 0 0 transparent;
	background:-webkit-gradient(linear, left top, left bottom, from(#444444), to(#111111));
	/* css3 borders */
    
    border: 1px solid #9C9C9C;
	box-shadow:inset 0px 0px 1px #e8edf0;
	-moz-box-shadow:inset 0px 0px 1px #e8edf0;
	-webkit-box-shadow:inset 0px 0px 1px #e8edf0;
}
/* tab starts here */

#menu li {
	float:left;
	display:block;
	position:relative;
	text-align:center;
	padding:4px 10px;
	margin:7px 30px 0 0;
	border:none;
}
#menu li:hover {
	border:1px solid #b7b7b7;
	padding:4px 9px;
	/*rounded corners  */
    
    border-radius:5px 5px 0 0;
	-moz-border-radius:5px 5px 0 0;
	-webkit-border-radius:5px 5px 0 0;
	/* css 3 gradient */
    background:#fff;
	background: -moz-linear-gradient(center top, #FFFFFF, #EDEDED) repeat scroll 0 0 transparent;
	background:-webkit-gradient(linear, left top, left bottom, from(#FFFFFF), to(#EDEDED));
}
#menu li a {
	font-size:14px;
	color: #999999;
	display:block;
	outline:0;
	text-decoration:none;
}
#menu li:hover a {
	color:#161616;
}
/* menu containers here  */

#menu .menu-container-1,#menu .menu-container-2,#menu .menu-container-3,#menu .menu-container-4 {
	margin:4px auto;
	float:left;
	position:absolute;
	left:-999em;
	text-align:left;
	padding:10px 5px;
	border:1px solid #b7b7b7;
	border-top:none;
	/* rounded corners */
    
    border-radius:0 5px 5px 5px;
	-moz-border-radius:0 5px 5px 5px;
	-webkit-border-radius:0 5px 5px 5px;
	/* gradient */
    background:#444444;
	background: -moz-linear-gradient(center top, #444444, #111111) repeat scroll 0 0 transparent;
	background:-webkit-gradient(linear, left top, left bottom, from(#444444), to(#111111));
}
#menu .menu-container-1 {
	width:140px;
}
#menu .menu-container-2 {
	width:280px;
}
#menu .menu-container-3 {
	width:420px;
}
#menu .menu-container-4 {
	width:560px;
}
#menu li:hover .menu-container-1, #menu li:hover .menu-container-2, #menu li:hover .menu-container-3, #menu li:hover .menu-container-4 {
	top:auto;
	left:-1px;
}
/* columns ici */

#menu .column-1, #menu .column-2 {
	display:inline;
	float:left;
	position:relative;
	margin:0 5px;
}
#menu .column-1 {
	width:130px;
}
#menu .column-2 {
	width:260px;
}
#menu .column-3 {
	width:390px;
}
#menu .column-4 {
	width:520px;
}
/* right menu */

#menu .menu-right {
	float:right;
	margin-right:0px;
}
#menu li .align-right {
	/*rounded corners */
    
    border-radius:5px 0 5px 5px;
	-moz-border-radius:5px 0 5px 5px;
	-webkit-border-radius:5px 0 5px 5px;
}
#menu li:hover .align-right {
	left:auto;
	right:-1px;
	top:auto;
}
/* menu h2, h3, p, etc.... */

#menu p, #menu h2, #menu h3, #menu ul li {
	line-height:21px;
	font-size:12px;
	text-align:left;
}
#menu p {
	line-height:18px;
	margin-bottom:10px;
	color:#F2E8E8;
}
#menu h3, #menu h2 {
	font-size:11px;
	margin:7px 0 14px 0;
	padding-bottom:5px;
	text-transform:uppercase;
	color: #999999;
}
#menu li:hover div a {
	box-shadow: 0 1px 0 #111111, 0 2px 0 #777777;
	color: #666666;
	font-size: 11px;
	padding-left: 6px;
}
#menu li:hover div a:hover {
	background: -moz-linear-gradient(#04ACEC, #0186BA) repeat scroll 0 0 transparent;
	background:-webkit-gradient(linear, left top, left bottom, from(#04ACEC), to(#0186BA));
	color: #FAFAFA;
	background:#04ACEC;
}
#menu li ul {
	box-shadow: 0 1px 0 #111111, 0 2px 0 #777777;
	list-style:none;
	padding:0;
	margin-bottom:12px;
}
#menu li ul li {
	float: none;
	font-size: 12px;
	line-height: 24px;
	margin: 0;
	padding: 0;
	position: relative;
	text-align: left;
	width: 130px;
}
#menu li ul li:hover {
	background: none;
	border: medium none;
	margin: 0;
	padding: 0;
}
/* login here */

#menu .form {
	margin:10px 0 0 45px;
}
#menu input {
	color:#e9e9e9;
	font-size:12px;
	outline:0 none;
	padding:9px;
	/* gradient */
    background:#6e6e6e;
	background:-moz-linear-gradient(top, #888, #575757);
	background:-webkit-gradient(linear, left top, left bottom, from(#888), to(#575757));
	/* css3 borders */
    border:1px solid #555;
	-moz-border-radius:10px;
	-webkit-border-radius:10px;
	/* css3 shadow effect */
    -moz-box-shadow:0 0 8px rgba(0, 0, 0, 0.1);
	-webkit-box-shadow:rgba(0, 0, 0, 0.1) 0px 0px 8px;
	box-shadow:rgba(0, 0, 0, 0.1) 0px 0px 8px;
}
#menu input:focus {
	background: none repeat scroll 0 0 #313131;
}
#menu input:hover {
	border-color: #000000;
}
#menu .submit input {
	background: -moz-linear-gradient(center top, #444444, #111111) repeat scroll 0 0 transparent;
	background:-webkit-gradient(linear, left top, left bottom, from(#444444), to(#111111));
	border-radius: 10px 10px 10px 10px;
	box-shadow: 0 0 1px #EDF9FF inset;
	color: #FADDDE;
	padding: 9px;
	width: 90px;
}
#menu .submit input:hover {
	background: -moz-linear-gradient(center top, #444444, #3D3A3A) repeat scroll 0 0 transparent;
	background:-webkit-gradient(linear, left top, left bottom, from(#444444), to(#3D3A3A));
	cursor: pointer;
}
#menu .submit input:active {
	background: -moz-linear-gradient(center top, #444444, #111111) repeat scroll 0 0 transparent;
	background:-webkit-gradient(linear, left top, left bottom, from(#444444), to(#111111));
	border: 1px solid #9C9C9C;
	color: #9C9C9C;
}
footer {
	background: none repeat scroll 0 0 rgba(0, 0, 0, 0.04);
	border: 1px solid rgba(0, 0, 0, 0.08);
	border-radius: 5px 5px 5px 5px;
	box-shadow: 0 3px 1px rgba(0, 0, 0, 0.02) inset, 0 1px 0 white;
	padding: 1.5em;
	bottom: 0;
	display: block;
	height: 40px;
	left: 0;
	position: fixed;
	width: 100%;
	z-index: 100000;
}
footer h2 {
	color: rgba(0, 0, 0, 0.8);
    text-shadow: 0 1px 0 white;
	font-size: 20px;
	font-weight: normal;
	left: 50%;
	margin-left: -400px;
	
	position: absolute;
	width: 500px;
	text-shadow: 1px #000000;
	font-family: 'PT Sans Narrow', Arial, sans-serif;
}
footer a.youhacked, a.youhacked:visited {
	background: url("http://youhack.me/demo/Apple%20itunes%20banner%20rotator/youhack.png") no-repeat scroll right top transparent;
	border: medium none;
	font-size: 12px;
	height: 70px;
	left: 50%;
	line-height: 31px;
	margin: 25px 0 0 110px;
	position: absolute;
	text-decoration: none;
	top: 0;
	width: 310px;
	color: #000000;
	letter-spacing: 1px;
	text-shadow: 1px #000000;
}