This is the step by step guide to create float image that will always show on your corner blog althought you drag side scroll bar.

1.log in to your dashboard--> layout- -> Edit HTML

2.Click on "Expand Widget Template"

3.Scroll down to where you see this:-

]]></b:skin>

4.Then put the below code above it.

#float_corner {
position:fixed;_position:absolute;bottom:0px;left:0px;clip:
inherit;_top:expression(document.documentElement.scrollTop+document.documentElement.clientHeight-this.clientHeight);_left:expression(document.documentElement.scrollLeft + document.documentElement.clientWidth - offsetWidth);}

Then it see like this.

#float_corner {
position:fixed;_position:absolute;bottom:0px;left:0px;clip:
inherit;_top:expression(document.documentElement.scrollTop+document.documentElement.clientHeight-this.clientHeight);_left:expression(document.documentElement.scrollLeft + document.documentElement.clientWidth - offsetWidth);}
]]></b:skin>

Note: "bottom", "left" are its position.you can change it with "top", "bottom", "left", "right"

5.Now put the below code before </body> tag.

<div id="float_corner">
<a href="http://2009bloggertemplates.blogspot.com"><img src="http://i626.photobucket.com/albums/tt346/wam8387/sun.jpg" border="0" /></a>
</div>

Note:
Replace "http://2009bloggertemplates.blogspot.com" and "http://i626.photobucket.com/albums/tt346/wam8387/sun.jpg" with your own details.

"http://i626.photobucket.com/albums/tt346/wam8387/sun.jpg" is image URL.

"http://2009bloggertemplates.blogspot.com" is a target URL for your image.

Save Template and preview your blog.