File Stream C#

using System;
using System.Xml;
using System.Xml.Serialization;
using System.IO;
public class SerializeXml {
    private static void Main() {
        CarList catalog = new CarList("New List", DateTime.Now.AddYears(1));
        Car[] cars = new Car[2];
        cars[0] = new Car("Car 1", 12342.99m);
        cars[1] = new Car("Car 2", 21234123.9m);
        catalog.Cars = cars;
        XmlSerializer serializer = new XmlSerializer(typeof(CarList));
        FileStream fs = new FileStream("CarList.xml", FileMode.Create);
        serializer.Serialize(fs, catalog);
        fs.Close();
        catalog = null;
        // Deserialize the order from the file.
        fs = new FileStream("CarList.xml", FileMode.Open);
        catalog = (CarList)serializer.Deserialize(fs);
        // Serialize the order to the Console window.
        serializer.Serialize(Console.Out, catalog);
    }
}
[XmlRoot("carList")]
public class CarList {
    [XmlElement("catalogName")]
    public string ListName;
    
    // Use the date data type (and ignore the time portion in the serialized XML).
    [XmlElement(ElementName="expiryDate", DataType="date")]
    public DateTime ExpiryDate;
    
    [XmlArray("cars")]
    [XmlArrayItem("car")]
    public Car[] Cars;
    public CarList() {
    }
    public CarList(string catalogName, DateTime expiryDate) {
        this.ListName = catalogName;
        this.ExpiryDate = expiryDate;
    }
}
public class Car {
    [XmlElement("carName")]
    public string CarName;
    
    [XmlElement("carPrice")]
    public decimal CarPrice;
    
    [XmlElement("inStock")]
    public bool InStock;
    
    [XmlAttributeAttribute(AttributeName="id", DataType="integer")]
    public string Id;
    public Car() {
    }
    public Car(string carName, decimal carPrice) {
        this.CarName = carName;
        this.CarPrice = carPrice;
    }
}