1.Login to your blogger dashboard--> layout- -> Edit HTML

2.Scroll down to where you see </head> tag .

3.Copy below code and paste it just before the </head> tag .

<script src='http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js?ver=1.3.2' type='text/javascript'/>

<script type='text/javascript'>
//<![CDATA[
$(function(){

// ***
// Scrolling background
// ***

// height of background image in pixels
var backgroundheight = 4000;

// get the current minute/hour of the day
var now = new Date();
var hour = now.getHours();
var minute = now.getMinutes();

// work out how far through the day we are as a percentage - e.g. 6pm = 75%
var hourpercent = hour / 24 * 100;
var minutepercent = minute / 30 / 24 * 100;
var percentofday = Math.round(hourpercent + minutepercent);

// calculate which pixel row to start graphic from based on how far through the day we are
var offset = backgroundheight / 100 * percentofday;

// graphic starts at approx 6am, so adjust offset by 1/4
var offset = offset - (backgroundheight / 1);

function scrollbackground() {
// decrease the offset by 1, or if its less than 1 increase it by the background height minus 1
offset = (offset < 1) ? offset + (backgroundheight - 1) : offset - 1;
// apply the background position
$('body').css("background-position", "50% " + offset + "px");
// call self to continue animation
setTimeout(function() {
scrollbackground();
}, 70
);
}

// Start the animation
scrollbackground();
});
//]]>
</script>

4.Now scroll down to where you see like this code:

body {
background:$bgcolor;
margin:0;
color:$textcolor;
font:x-small Georgia Serif;
font-size/* */:/**/small;
font-size: /**/small;
text-align: center;
}

Note:above code can be different in your template.But important part is body { .

5.Replace above code with below code:

body {
background:url(http://1.bp.blogspot.com/_4HKUHirY_2U/Suj7uR3ZKfI/AAAAAAAAAGU/R8pnF8urjTk/bgscroll.jpg);
color:$textcolor;
font:x-small Georgia Serif;
font-size/* */:/**/small;
font-size: /**/small;
text-align: center;
}

Note: You can use any suitable image instead of above image.

6.Click on save template and you are done.

Demo