Only posts from one category

Hi,
I’m trying to show post from one single category on the right side via the category widget. Please help.

I have tried this tips that I have seen several times on the net. But I cannot get it to work: Were 365 is the ID for the specific category I like show posts from.

function filter_home_page_pots($query) {
if ( !is_admin() && $query->is_main_query() ) {
if ($query->is_home) {
$query->set( ‘cat’, get_cat_ID(‘265’));
}
}
}

add_action(‘pre_get_posts’,’filter_home_page_pots’);