Position Change on Hover

For doing this we need two image. 

Fist one will be visible bydefault and scecond will appear on hover.
Now we need to add both image in single image, on top part add default image and in bottom part add hover image.
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\
#onHover_adms a{
background:url("previous.png") 0 0 no-repeat;
font-size:25px;
padding-right:18px;
}
#onHover_adms a:hover{
background-position:0px -29px;
}

<div id="onHover">
<a href="#">&nbsp;</a>
</div>

Thanks........................