You can Install This Widget Easily in your Blog By Following These Simple Steps....

Before you edit any template it's better to keep a Backup..
So First Backup your Template. Now Go To Design>Edit Html>Select Expand Widgets...

Demo : Click Here 

Step 1 : The CSS You Need To Search The Following Piece Of Code By Pressing [Ctrl+F]


]]></b:skin>
Now Paste The Bellow Code Just Before it.

/*    ColorBox Core Style:    The following CSS is consistent between example themes and should not be altered. */ #colorbox, #cboxOverlay, #cboxWrapper{position:absolute; top:0; left:0; z-index:9999; overflow:hidden;} #cboxOverlay{position:fixed; width:100%; height:100%;} #cboxMiddleLeft, #cboxBottomLeft{clear:left;} #cboxContent{position:relative;} #cboxLoadedContent{overflow:auto;} #cboxTitle{margin:0;} #cboxLoadingOverlay, #cboxLoadingGraphic{position:absolute; top:0; left:0; width:100%;} #cboxPrevious, #cboxNext, #cboxClose, #cboxSlideshow{cursor:pointer;} .cboxPhoto{float:left; margin:auto; border:0; display:block;} .cboxIframe{width:100%; height:100%; display:block; border:0;} /*
   User Style:
   Change the following styles to modify the appearance of ColorBox.  They are
   ordered & tabbed in a way that represents the nesting of the generated HTML.
*/
#cboxOverlay{background:#000;opacity:0.5 !important;}
#colorbox{
        box-shadow:0 0 15px rgba(0,0,0,0.4);
       -moz-box-shadow:0 0 15px rgba(0,0,0,0.4);
        -webkit-box-shadow:0 0 15px rgba(0,0,0,0.4);
       }
   #cboxTopLeft{width:14px; height:14px; background:url(http://imgboot.com/images/cybersidh/controls.png) no-repeat 0 0;}
   #cboxTopCenter{height:14px; background:url(http://imgboot.com/images/cybersidh/border.png) repeat-x top left;}
   #cboxTopRight{width:14px; height:14px; background:url(http://imgboot.com/images/cybersidh/controls.png) no-repeat -36px 0;}
   #cboxBottomLeft{width:14px; height:43px; background:url(http://imgboot.com/images/cybersidh/controls.png) no-repeat 0 -32px;}
   #cboxBottomCenter{height:43px; background:url(http://imgboot.com/images/cybersidh/border.png) repeat-x bottom left;}
   #cboxBottomRight{width:14px; height:43px; background:url(http://imgboot.com/images/cybersidh/controls.png) no-repeat -36px -32px;}
   #cboxMiddleLeft{width:14px; background:url(http://imgboot.com/images/cybersidh/controls.png) repeat-y -175px 0;}
   #cboxMiddleRight{width:14px; background:url(http://imgboot.com/images/cybersidh/controls.png) repeat-y -211px 0;}
   #cboxContent{background:#fff; overflow:visible;}
       #cboxLoadedContent{margin-bottom:5px;}
       #cboxLoadingOverlay{background:url(http://imgboot.com/images/cybersidh/loadingbackground.png) no-repeat center center;}
       #cboxLoadingGraphic{background:url(http://imgboot.com/images/cybersidh/loading.gif) no-repeat center center;}
       #cboxTitle{position:absolute; bottom:-25px; left:0; text-align:center; width:100%; font-weight:bold; color:#7C7C7C;}
       #cboxCurrent{position:absolute; bottom:-25px; left:58px; font-weight:bold; color:#7C7C7C;}
       #cboxPrevious, #cboxNext, #cboxClose, #cboxSlideshow{position:absolute; bottom:-29px; background:url(http://imgboot.com/images/cybersidh/controls.png) no-repeat 0px 0px; width:23px; height:23px; text-indent:-9999px;}
       #cboxPrevious{left:0px; background-position: -51px -25px;}
       #cboxPrevious.hover{background-position:-51px 0px;}
       #cboxNext{left:27px; background-position:-75px -25px;}
       #cboxNext.hover{background-position:-75px 0px;}
       #cboxClose{right:0; background-position:-100px -25px;}
       #cboxClose.hover{background-position:-100px 0px;}
       .cboxSlideshow_on #cboxSlideshow{background-position:-125px 0px; right:27px;}
       .cboxSlideshow_on #cboxSlideshow.hover{background-position:-150px 0px;}
       .cboxSlideshow_off #cboxSlideshow{background-position:-150px -25px; right:27px;}
       .cboxSlideshow_off #cboxSlideshow.hover{background-position:-125px 0px;}
/*-----------------------------------------------------------------------------------*/
/*    box popup
/*-----------------------------------------------------------------------------------*/
#subscribe {
    font: 12px/1.2 Arial,Helvetica,san-serif;
}
#subscribe a,
#subscribe a:hover,
#subscribe a:visited {
    text-decoration:none;
}
.box-title {
   color: #2C2D31;
   font-size: 20px;
   font-weight: bold;
   margin: 10px 0;
   text-align: center;
}
.box-tagline {
   color: #999;
   font-size: 14px;
   margin: 0;
   text-align: center;
}
#subs-container {
    padding: 35px 0 30px 0;
    position: relative;
}
.box-side {
    width: 170px;
    text-align: center;
}
.box-side.left {
   padding: 0 30px 0 15px;
    border-right: 1px solid #ecedf3;
}
.box-side.right {
    float: right;
   margin-top: -223px;
    margin-right: 10px;
}
.box-icon {
    width: 72px;
    height: 54px;
    padding: 6px 0 0 0;
    margin: 0 auto;
}
.box-icon a.rss{
    display: block;
    width: 70px;
    height: 56px;
    margin: 0 auto;
}
.box-icon a{
    display: block;
    width: 72px;
    height: 54px;
}
.box-icon a.email img,
.box-icon a.rss img {
   margin: -5px 0 0;
    border: 0 none;
}
.box-side h4,
.box-side h4 a {
    font-size: 14px;
    line-height: 14px;
    color: #f26535;
    font-weight: bold;
}
.box-side h4 { margin: 20px 0 10px 0; }
.box-side h5 {
    font-size: 11px;
    color: #5e6066;
    line-height: 18px;
    margin: 0 0 20px 0;
}
a.sub {
   background: url("http://imgboot.com/images/cybersidh/subscribebutton.png") no-repeat scroll 0 0 transparent;
   color: #996633;
   display: block;
   height: 44px;
   line-height: 29px;
   margin: 0 auto;
   text-indent: -999em;
   width: 130px;
}
.box-side h4 a:hover {
    color: #f26535;
}
#box-or {
   background: #fff;
   font-size: 12px;
   font-weight: bold;
   height: 25px;
   line-height: 25px;
   margin: -115px 0 0 208px;
   position: absolute;
   width: 20px;
}
a:link, a:visited {
border:none;
}
.demo {
display:none;
}


Now Hit Prievew, If Every Thing Works Fine then Save The Template..

Step 2 : The Html In This Part you'll add the widget to your Blog !!
Goto :: Design>Page Elements>Add Gadget>Html/Javascript
Now Paste The Following Code In It.

<script src='http://ajax.googleapis.com/ajax/libs/jquery/1.5/jquery.min.js'></script> <script src="http://sidharth12.googlecode.com/files/jquery.colorbox-min.js"></script> <script type="text/javascript"> jQuery(document).ready(function(){    if (document.cookie.indexOf('visited=true') == -1) {        var fifteenDays = 1000*60*60*24*15;        var expires = new Date((new Date()).valueOf() + fifteenDays);        document.cookie = "visited=true;expires=" + expires.toUTCString();    $.colorbox({width:"480px", inline:true, href:"#subscribe"});        } }); </script>     <!-- This contains the hidden content for inline calls -->     <div style='display:none'>         <div id='subscribe' style='padding:10px; background:#fff;'>         <h2 class="box-title">Never Miss Any Update From Us!</h2>                <h2 class="box-tagline">Enrich Your Inbox.[402+ Readers]</h2><br/>                <form style="border:1px solid #ccc;padding:3px;text-align:center;" action="http://feedburner.google.com/fb/a/mailverify" method="post" target="popupwindow" onsubmit="window.open('http://feedburner.google.com/fb/a/mailverify?uri=ILibrary', 'popupwindow', 'scrollbars=no,width=560,height=540');return true"><p>Enter your email address:</p><p><input type="text" style="width:140px" name="email"/></p><input type="hidden" value="ILibrary" name="uri"/><input type="hidden" name="loc" value="en_US"/><input type="submit" value="Subscribe" /><p>Delivered by <a href="http://feedburner.google.com" target="_blank">FeedBurner</a> | Powered By <a href="http://www.mybloggertricks.com">MBT</a></p></form>         <br/><h2 class="box-tagline">Subscribe us today and get Quality Articles for free.</h2> </div> </div>

Important :
Remove The Red Colored ILibrary With You FeedBurner ID.
Ignore The Line In Pink If Your Blog Already has JQuery. 

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