how to set a page to A4 layout

Hi all,

I am formatting an XSL layout in A4 size, however it is taking default
dimensions.
In the printout , around 5 cms from top and 6 cms from the bottom of the
page is not being utilized.
How do we make the content fit exactly into the page. ie. i would like to
only set my top and bottom margins to 1cm each.

Help needed urgently..

Regards
Rao