1.Log in to your dashboard--> layout- -> Edit HTML.
2.Click on "Expand Widget Templates"
3.Scroll down to where you see this:
<span class='post-author vcard'>
<b:if cond='data:top.showAuthor'>
<data:top.authorLabel/>
<span class='fn'><data:post.author/></span>
</b:if>
</span>
4.Replace <data:post.author/> with below code:
<a href="URL OF YOUR BLOG"><img src="URL OF YOUR PICTURE" /></a>
5.Click on "Save Templates" and refresh your site.
Note : Remember to give your real information to URL OF YOUR BLOG and URL OF YOUR PICTURE.
Oh Man You aree the great Blog master thankssssssssss So Much For This
Oh man I am gona die its tooooooooooooo Coooooooool Boss Thankssssss A Lot........:) Check Out Mine http://onsecrethunt.blogspot.com/