how can i order the category by date

When the instance of WP_Query is not a variable on the PHP file you are working on it tends to be the “main” query and to edit this instance of the WP_Query you will need to Hook to the pre_get_posts action and change what you need there. Here is an Exemple:

<?php
add_action( 'pre_get_posts', 'q166401_pre_get_posts', 10, 1 );

/**
 * On this case I will filter only the Home and the main query
 * @param  WP_Query $query The query object
 */
function q166401_pre_query( $query ){
    // Stop this function when it's not Home or it's not the main query
    if ( ! $query->is_home() || ! $query->is_main_query() ) {
        return;
    }

    // Here you will set the filters you want
    $query->set( 'order', 'ASC' );
}

If you have any problems referrer to the codex page related to this hook.