Add ListItem at zero Index as Please Select in DropDownList after Binding it from Database in ASP.Net

Please refer this

C#

private void PopulateDropDownList()
{
    string constr = ConfigurationManager.ConnectionStrings["conString2"].ConnectionString;
    using (SqlConnection con = new SqlConnection(constr))
    {
        using (SqlCommand cmd = new SqlCommand("SELECT FirstName,EmployeeID FROM Employees", con))
        {
            using (SqlDataAdapter da = new SqlDataAdapter(cmd))
            {                
                DataSet ds = new DataSet();
                da.Fill(ds);
                this.ddlEmployees.DataTextField = "FirstName";
                this.ddlEmployees.DataValueField = "EmployeeID";
                this.ddlEmployees.DataSource = ds;
                this.ddlEmployees.DataBind();
                this.ddlEmployees.Items.Insert(0, new System.Web.UI.WebControls.ListItem("Please Select", "0"));
            }
        }
    }
}