how to barcode reader work

using Bytescout.BarCodeReader;

namespace SimpleWebTestSharp
{
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
Image1.ImageUrl = "BarcodePhoto.jpg";

Reader reader = new Reader(Server.MapPath("BarcodePhoto.jpg"));
foreach (FoundBarcode barcode in reader.FoundBarcodes)
ListBox1.Items.Add(String.Format("{0} : {1}", barcode.Type, barcode.Value));
}
}
}