Add multiple item in woocomerce order API in .Net Core

I am creating an api in .net core api for woocomerce order api, where i am sending the parameters from class object.

But i am getting difficulties for adding multiple item.

public async Task<Response> OrderAdd(OtcOrder order)
{
    Response response = new Response();
 
    RestAPI rest = new RestAPI(_wooCommerceBaseUrl, _wooCommerceKey, _wooCommerceSecret);
    WCObject wc = new WCObject(rest);
    // Instantiate an object of the Order class
    Order orders = new Order();
    orders.payment_method = order.payment_method;
    orders.payment_method_title = order.payment_method_title;
    orders.set_paid = order.set_paid;
    orders.billing.first_name = order.billing.first_name;
    orders.billing.last_name = order.billing.last_name;
    orders.billing.address_1 = order.billing.address_2;
    orders.billing.address_2 = order.billing.address_2;
    orders.billing.city = order.billing.city;
    orders.billing.state = order.billing.state;
    orders.billing.postcode = order.billing.postcode;
    orders.billing.country = order.billing.country;
    orders.billing.email = order.billing.email;
    orders.billing.phone = order.billing.phone;
    orders.shipping.first_name = order.shipping.first_name;
    orders.shipping.last_name = order.shipping.last_name;
    orders.shipping.address_1 = order.shipping.address_1;
    orders.shipping.address_2 = order.shipping.address_2;
    orders.shipping.city = order.shipping.state;
    orders.shipping.state = order.shipping.state;
    orders.shipping.postcode = order.shipping.postcode;
    orders.shipping.country = order.shipping.country;         
    
    orders.line_items =  order.line_items;         
    // Pass the order object as a parameter to the API call
    var res= wc.Order.Add(orders, null);
    return response;
}