Insert code into text box from .cs class

Hi
I do not want to use the listview dataview etc in .NET2.0
Can any one tell me how to insert the following code in a .cs class into a textbox on a aspx page

public CustomerBLL GetCustomerByID(int orderNumber)
            {
            SqlConnection con = new SqlConnection(DBConn);
            SqlCommand cmd = new SqlCommand("ats_SelectCustomerDetails", con);
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.Parameters.Add(new SqlParameter("@CustomerID", SqlDbType.Int, 4));
            cmd.Parameters["@CustomerID"].Value = orderNumber;

            try
                {
                con.Open();
                SqlDataReader rdr = cmd.ExecuteReader(CommandBehavior.SingleRow);
                rdr.Read();
                CustomerBLL cust = new CustomerBLL(
                    (int)rdr["OrderNumber"],
                    (string)rdr["CustomerEmail"],
                    (string)rdr["CustomerPassword"],
                    (string)rdr["CustomerName"],
                    (string)rdr["CustomerPosition"],
                    (string)rdr["CustomerCompany"],
                    (string)rdr["CustomerAddress"],
                    (string)rdr["CustomerCity"],
                    (string)rdr["CustomerCounty"],
                    (string)rdr["CustomerPostCode"],
                    (string)rdr["CustomerCountry"],
                    (string)rdr["CustomerPhone"]);
                rdr.Close();
                return cust;
                }
            catch (SqlException)
                {
                throw new ApplicationException("Sorry an error has occured<br /> and we cannot process your request.<br /> Error code 1001");
                }
            finally
                {
                if (con.State == ConnectionState.Open)
                    {
                    cmd.Dispose();
                    con.Close();
                    con.Dispose();
                    }

textbox text="Need to add code her"