where should we put a portlt war file to make sure that it will install

Hi
Thank you for reading my post.
where should i put a war file to make sure that it will be installed 
into portal system next time that
portal start ?

or , better i ask how we can deploy a portlet using ANT (i know that ant 
copy the portlet into the PlutoDomain) that make our portlet available 
in portlet list ?

thanks