How to content Lock a Div Only [HELP]

[amberlamps]

Yes I need some help Ive Been trying to implement this content locker [Provide by pyronaut] *edit cannot link yet

This the .js goes in the header

<script src="http://ajax.microsoft.com/ajax/jquery/jquery-1.4.2.min.js" type="text/javascript"></script>
<script type="text/javascript">

    var Delay = 10;//Seconds after them clicking the link, the gateway vanishes. 
    
    function setupgateway()
    {
        var Left = $(window).width() /2;
        Left = Left - $('#gatewaydiv').width()/2;
        
        var Top = $(window).height() /2;
        Top = Top - $('#gatewaydiv').height()/2;
        
        $('#gatewaydiv').css('top', Top+'px').css('left', Left+'px').css('display', 'inline');
        $('#gatewayDimmer').width($('html').width());
        $('#gatewayDimmer').height($('html').height());
        $('#gatewayDimmer').css('display','block');
    }
    
    function removegateway()
    {
        $('#gatewaydiv').css('display', 'none');
        $('#gatewayDimmer').css('display','none');
    }
    
    $(document).ready(function()
    {
        $('.offerlink').click(function()
        {
            setTimeout('removegateway()', Delay*1000);
        });
        
        setupgateway();
    });
</script>

This the css

<style>

    body
    {
        background-image:url('http://i41.tinypic.com/29zvocy.jpg');
        background-repeat:repeat;
        height:100%;
        margin:0;
    }

    #mainContent
    {
        background-color:white;
        margin-left:auto;
        margin-right:auto;
        margin-top:30px;
        width:700px;
        border:3px solid #CDCDCD;
        text-align:center;
    }

    #gatewaydiv
    {
        background-image:url("http://i41.tinypic.com/2znsvti.png");
        background-repeat:no-repeat;
        width:500px;
        height:300px;
        padding:20px;
        position:absolute;
        display:none;
        background-color:#FFFFFF;
        border:solid 4px gray;
        text-align:center;
        font-family:arial;
    }

    #gatewaydiv h1
    {
        font-size:35px;
        color:#cc0000;
    }

    #gatewayMessage
    {
        font-size:18px;
    }
    
    .offerlink
    {
        color:red;
        font-weight:bold;
    }
    
    #OfferList
    {
        margin:0;
        padding:0;
    }
    
    #OfferList
    {
        list-style:none;
    }

    #gatewayDimmer
    {
        background-color:#000000;
        opacity:0.8;
        display:none;
        position:absolute;
        top:0;
    }

    
</style>

This is the body

<div id="gatewayDimmer">
</div>

<div id="gatewaydiv">
    <ul id="OfferList">
    <h1>Do an offer or DAI!</h1>
    <span id="gatewayMessage">If you wish to see your friends alive. You will fill out an offer right now!</span>
    <br /><br />
    <li><a href="http://www.wachahost.com" class="offerlink" target="blank">Cheap Web Hosting</a></li>
    <li><a href="http://peerfly.com/x/0/1076/3696/"  class="offerlink" target="blank">Free Apple Ipad</a></li>
    <li><a href="http://www.google.com" class="offerlink" target="blank">Google</a></li>
    </ul>
    <br /><br />
    After completing an offer. Please wait up to a minute for it to register.<br />
    Thank you!
</div>

Okay now that you got the whole script, I need help in applying this to only a div. I do not want this to lock down the whole page just a Div I say .

now the div i want to lock down. looks like this

<div id="I am div" class="style"></div>