Create a WooCommerce Order Dynamically

create-woocommerce-order-dynamically.php

<?php
/*
 * Create order dynamically
 */
add_action( 'woocommerce_before_checkout_form', 'create_order' );

function create_order() {
	
	global $woocommerce;
	
	$address = array(
		'first_name' => 'Remi',
		'last_name'  => 'Corson',
		'company'    => 'Automattic',
		'email'      => '[email protected]',
		'phone'      => '123-123-123',
		'address_1'  => '123 Main Woo st.',
		'address_2'  => '100',
		'city'       => 'San Francisco',
		'state'      => 'Ca',
		'postcode'   => '92121',
		'country'    => 'US'
	);
	
	// Now we create the order
	$order = wc_create_order();
	
	// The add_product() function below is located in /plugins/woocommerce/includes/abstracts/abstract_wc_order.php
	$order->add_product( get_product( 99 ), 1); // Use the product IDs to add
	
	// Set addresses
	$order->set_address( $address, 'billing' );
	$order->set_address( $address, 'shipping' );
	
	// Set payment gateway
	$payment_gateways = WC()->payment_gateways->payment_gateways();
	$order->set_payment_method( $payment_gateways['bacs'] );
	
	// Calculate totals
	$order->calculate_totals();
	$order->update_status( 'Completed', 'Order created dynamically - ', TRUE);
}

Where do i need to add this and how do i call the function? sorry im a new coder