on the home page to display only one category

on the home page to display only one category
where to register the function:

<?php if ( !in_category('1') ) continue; ?>

Hi!

Perhaps, you may insert this code into theloop.php file located inside the theme directory. I would also recommend you enable the WP_DEBAG option from WordPRess to be aware about any warnings or errors during editing the theme.

Thank You.
in theloop.php:
<?php if (is_home()) { query_posts($query_string.'&cat=1&showposts=2'); }
before
<?php }
while (have_posts()) : the_post(); ?>