how to redirect query string value to paypal standard payment method

 $query = array();
    $query['notify_url'] = 'http://yourwesite.com/ipn';
    $query['cmd'] = '_cart';
    $query['upload'] = '1';
    $query['business'] = 'nayak.bikash@yahoo.com';
    $query['address_override'] = '1';
    $query['first_name'] = $first_name;
    $query['last_name'] = $last_name;
    $query['email'] = $email;
    $query['address1'] = $ship_to_address;
    $query['city'] = $ship_to_city;
    $query['state'] = $ship_to_state;
    $query['zip'] = $ship_to_zip;
    $query['item_name_'.$i] = $item['description'];
    $query['quantity_'.$i] = $item['quantity'];
    $query['amount_'.$i] = $item['info']['price'];

    // Prepare query string
    $query_string = http_build_query($query);

    header('Location: https://www.paypal.com/cgi-bin/webscr?' . $query_string);