{CODE type:php;}<?php if (have_posts()) : ?>{/CODE}
and add this code:
{CODE type:php;}query_posts(‘cat=3’);{/CODE}
So we got this:
{CODE type:php;}<?php query_posts(‘cat=3’); if (have_posts()) : ?>{/CODE}
Where ‘cat=3’ is ID of Your category. To find out what is your Blog ID. In admin panel click on Posts -> Categories -> Blog and view URL: