Drop down menu help

[User4Fun]

I would appreciate any help I can get. I am trying to add a drop down menu under the following navigation bar.

#nav_bar {height:62px;margin:0 auto;overflow:hidden;width:988px;}

ul#menu_items {background:transparent url(images/nav_bar.png) no-repeat scroll left 0;float:left;list-style-image:none;list-style-position:outside;list-style-type:none;margin:0 0 0 -5px;padding:0;width:964px;}

ul#menu_items li a {background-image:url(images/nav_bar.png);background-repeat:no-repeat;display:block;float:left;height:60px;text-indent:-9999px;}

ul#menu_items li a.home {background-position:-50px 0;margin-left:50px;width:105px;}
ul#menu_items li a.ops {background-position:-155px 0;width:152px;}
ul#menu_items li a.deten {background-position:-307px 0;width:141px;}
ul#menu_items li a.cor {background-position:-448px 0;width:167px;}
ul#menu_items li a.admin {background-position:-615px 0;width:183px;}
ul#menu_items li a.extras {background-position:-798px 0;width:145px;}

html if it helps

<ul id="menu_items">
<li><a href="home.php" class="home">HOME</a></li>
   
<li><a href="ops.php" class="ops">OPS</a></li>
    <ul>
    <li><a href="1.htm">1</a></li>
    <ul>
    <li><a href="2.htm">2</a></li>
    <ul>
    <li><a href="3.htm">3</a></li>
    </ul>

<li><a href="det.php" class="deten">DET</a></li>
    <ul>
    <li><a href="4.htm">4</a></li>
    <ul>
    <li><a href="5.htm">5</a></li>
    <ul>
    <li><a href="6.htm">6</a></li>
    </ul>

<li><a href="cor.php" class="cor">COR</a></li>
    <ul>
    <li><a href="7.htm">7</a></li>
    <ul>
    <li><a href="8.htm">8</a></li>
    <ul>
    <li><a href="9.htm">9</a></li>
    </ul>

<li><a href="admin.php" class="admin">ADMIN</a></li>
    <ul>
    <li><a href="10.htm">10</a></li>
    <ul>
    <li><a href="11.htm>11</a></li>
    <ul>
    <li><a href="12.htm">12</a></li>
    </ul>

<li><a href="extras/index.php" class="extras">EXTRAS</a></li>
    <ul>
    <li><a href="13.htm">13</a></li>
    <ul>
    <li><a href="14.htm">14</a></li>
    <ul>
    <li><a href="15.htm">15</a></li>
    </ul>
</ul>

Thank you very much

 

[bcee]

Close your UL tags for a start.

I highly recommend using in-browser HTML validation, it will alert you of these simple mistakes.