by placing u mean, the viewpoint (showing) of the image. right?
Yes, by placing it I meant position it.
What I posted above was just an explanation of how the background-position property works. It can also take on % values as well.
However with sprites it gets a little more complicated because you are using the pseudo :hover (and optionally :focus and :active) to control when those background positions happen.
Here is a very simple example of a three state sprite using all three of those pseudo classes.
In [this recent thread I put together another example for someone else. There is a link to the test page in there and it is using [URL="http://www.css-lab.com/test/bades/site_images/nav_sprite.jpg"]this sprite](http://www.sitepoint.com/forums/showpost.php?p=4737543&postcount=26).
It will be best to experiment with some thing simple first until you get a firm understanding of how it all works.
Hope that helps!