Fixing a Header in Datagrid

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

/// <summary>
/// Summary description for DataGridSource
/// </summary>
public class DataGridSource
{
    private string _col1Data;
    public string Col1Data 
    {
        get { return _col1Data; }
        set { _col1Data = value; } 
    }
    private string _col2Data;
    public string Col2Data 
    {
        get { return _col2Data; }
        set { _col2Data = value; } 
    }
    private string _col3Data;
    public string Col3Data 
    {
        get { return _col3Data; }
        set { _col3Data = value; } 
    }
}