1 Pertama, masuk dulu ke halaman Edit HTML, jangan lupa memberi tanda centang pada "Expand Widget Templates"
2. Cari kode ini </head>
3. Kemudian ganti dengan kode dibawah ini

<!--Related Posts with thumbnails Scripts and Styles Start-->
<b:if cond='data:blog.pageType == &quot;item&quot;'>
<style type="text/css">
#related-posts {
float:center;
text-transform:none;
height:100%;
min-height:100%;
padding-top:5px;
padding-left:5px;
}

#related-posts h2{
font-size: 1.6em;
font-weight: bold;
color: black;
font-family: Georgia, &#8220;Times New Roman&#8221;, Times, serif;
margin-bottom: 0.75em;
margin-top: 0em;
padding-top: 0em;
}
#related-posts a{
color:black;
}
#related-posts a:hover{
color:black;
}

#related-posts a:hover {
background-color:#d4eaf2;
}
</style>
<script src='http://blogergadgets.googlecode.com/files/relatedthumbs21.js' type='text/javascript'/>
</b:if>
<!--Related Posts with thumbnails Scripts and Styles End-->
</head>

4.Lalu cari kode:

<div class='post-footer-line post-footer-line-

 atau

 <p class='post-footer-line post-footer-line-1'>

5.Masukan kode dibawah ini dibawah Salah Satu dari kode diatas yang kalian:

<!-- Marquee Serbablog Related Posts with Thumbnails Code Start-->
<b:if cond='data:blog.pageType == &quot;item&quot;'>
<div id='related-posts'>
<b:loop values='data:post.labels' var='label'>
<b:if cond='data:label.isLast != &quot;true&quot;'>
</b:if>
<b:if cond='data:blog.pageType == &quot;item&quot;'>
<script expr:src='&quot;/feeds/posts/default/-/&quot; + data:label.name + &quot;?alt=json-in-script&amp;callback=related_results_labels_thumbs&amp;max-results=12&quot;' type='text/javascript'/></b:if></b:loop>
<h3><b>Related Posts</b></h3>
<marquee align='center' behavior='alternate' direction='left' onmouseout='this.start()' onmouseover='this.stop()' scrollamount='2' width='100%'>
<script type='text/javascript'>
var currentposturl=&quot;<data:post.url/>&quot;;
var maxresults=10;
var relatedpoststitle=&quot;&quot;;
removeRelatedDuplicates_thumbs();
printRelatedLabels_thumbs();
</script></marquee>
</div><div style='clear:both'/>
</b:if>
<b:if cond='data:blog.url == data:blog.homepageUrl'><b:if cond='data:post.isFirstPost'>
<a href='http://serba-seru.blogspot.com/2010/02/thumbnail-related-posting-with-marquee.html' style='display:none;'>Thumbnail Related Post</a>
<a href='http://www.bloggerplugins.org/' style='display:none;'>blogger tutorials</a>
</b:if>
</b:if>
<!-- Marquee Serbablog Related Posts with Thumbnails Code End--> 

*Untuk mengganti jumlah artikel yang berjalan,ganti angka dalam kode:

var maxresults=10;

Semoga berhasil dan bermanfaat