How show a single Category on the Homepage

Hi

I want show only one category at the homepage. I found this:

"In the index.php just BELOW

<? php if (have_posts ()): while (have_posts ()): the_post ();?>

insert

<? php if (in_category ('XXXXXXX')) {?>

and just ABOVE the line <? php endwhile; ?>

insert

<? php}?>"

I tried this in the theloop.php file and the homepage shows single category correctly, but when click other category shows nothing.

Can anyone help me with this little issue?

Sorry my english, thanks
Best regards