居中弹出一个层，打开一个文件。

<style type="text/css">
.mydiv {
background-color: #A3CC4F;
border: 1px solid #666666;
padding:3px;
font-size: 12px;
z-index:999;
width: 960px;
height: 550px;
left:50%;
top:50%;
margin-left:-480px!important;/*FF IE7 该值为本身宽的一半 */
margin-top:-275px!important;/*FF IE7 该值为本身高的一半*/
margin-top:0px;
position:fixed!important;/* FF IE7*/
position:absolute;/*IE6*/
_top:       expression(eval(document.compatMode &&
            document.compatMode=='CSS1Compat') ?
            documentElement.scrollTop + (document.documentElement.clientHeight-this.offsetHeight)/2 :/*IE6*/
            document.body.scrollTop + (document.body.clientHeight - this.clientHeight)/2);/*IE5 IE5.5*/
}
.bg,.popIframe {
background-color: #666; display:none;
width: 150%;
height: 100%;
left:0;
top:0;/*FF IE7*/
filter:alpha(opacity=50);/*IE*/
opacity:0.5;/*FF*/
z-index:1;
position:fixed!important;/*FF IE7*/
position:absolute;/*IE6*/
_top:       expression(eval(document.compatMode &&
            document.compatMode=='CSS1Compat') ?
            documentElement.scrollTop + (document.documentElement.clientHeight-this.offsetHeight)/2 :/*IE6*/
            document.body.scrollTop + (document.body.clientHeight - this.clientHeight)/2);
}
.popIframe {
filter:alpha(opacity=0);/*IE*/
opacity:0;/*FF*/
}
#tl{height:22px;padding:3px 6px 3px 10px;font-size:15px;font-weight:bold;font-family:黑体; color:#FFFFFF;}
#tlleft{float:left; height:16px;}
#tlright{float:right; width:16px; height:16px;}
</style>
<script type="text/javascript">
<!--
 function showDiv(url){

document.getElementById('card').src =url;
document.getElementById('popDiv').style.display='block';
document.getElementById('bg').style.display='block';
document.getElementById('popIframe').style.display='block';
document.body.style.overflow='hidden';
}

function closeDiv(){
document.getElementById('popDiv').style.display='none';
document.getElementById('bg').style.display='none';
document.getElementById('popIframe').style.display='none';
document.body.style.overflow='';
document.getElementById('card').src ="";
}
//-->
</script>

<A href="javascript:void(0);" onclick='showDiv("20113474354145.doc");'>点击</A>
<div id="popDiv" class="mydiv" style="display:none;">
<div  id="tl">
  <div id="tlleft"></div>
  <div id="tlright"><a  href="javascript:void(0);" onclick="javascript:closeDiv()"><img src="../images/close2.gif" border="0" alt="关闭窗口"></a></div>
</div>
<iframe id='card'  frameborder='0' height=544 width=954></iframe></div>
<div id="bg" class="bg" style="display:none;"></div>
<a  href="javascript:closeDiv()"><iframe id='popIframe' class='popIframe' frameborder='0'></iframe></a>