Class reference (associations)

i want to know whether this code correct? or any improvments?. i want to place a order which refer the customer customer class to get customer id . i used following method to do it .code works fine. so i want know whether i use object oriented concept correctly.

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;
using System.Data.SqlClient;

///

/// Summary description for TCO
///

namespace TCO {

    public class Customer

{

    private string _customerID;
    private string _customerName;
    private string _customerAddress;
        

        public string CustomerID
        {
        get
        {
            return _customerID;
        }
        set
        {
            _customerID = value;
        }
        }

        public string customerName
        {
        get
        {
            return _customerName;

        }
        set
        {
            _customerName = value;
        }

        }
        public string customerAddress
        {
        get
        {
            return _customerAddress;
        }
        set
        {
            _customerAddress = value;
        }
        }
    

        
    public Customer()
    {
    
    }

    public string selectCustomer(string CName)
     {
         
    string C_ID="";
        
    SqlConnection conn = new SqlConnection(@"server=home; integrated security = true; database = test");
         
    string sqlselect = @"select CusID from testCustomer where CusName = '"+CName+"' ";
        
        SqlDataReader reader = null;
        
   
        conn.Open();
        
    SqlCommand cmd = new SqlCommand(sqlselect, conn);
        
    reader = cmd.ExecuteReader();

        while (reader.Read())
        {
            C_ID = reader.GetValue(0).ToString();
        }
        return C_ID;
    
    }
    


    public void Insert()
        

    {
        
    SqlConnection conn = new SqlConnection(@"server=home; integrated security = true; database = test");
        string sqlins = @"insert into testCustomer(CusID,CusName,CusAddress)values('" + _customerID + "','" + _customerName + "','" + customerAddress + "')";

        SqlCommand cmd = new SqlCommand(sqlins,conn);


        try
        {

            conn.Open();
            cmd.ExecuteNonQuery();
        }
        catch (SqlException ex)
        {
            
        }
        finally {

            conn.Close();
        }



    }
    
       

    
    
}

    public class Order
    {

        
        private string _OrderID;
        private string _Quantity;
        private string _OrderDetails;
        private string _OrderCustomerName;

        public string OrderID
        {
            get {

                return _OrderID;
            }
            set {

                _OrderID = value;
            
            }
        
        }
        public string Quantity
        {

            get {

                return _Quantity;
            
            }
            set
            {
                _Quantity = value;
            
            }
        }

        public string OrderDetiails
        {
            get
            {
                return _OrderDetails;
            }
            set
            {

                _OrderDetails = value;
            }
        }

        public string OrderCustomerName
        {

            get
            {
                return _OrderCustomerName;
            
            }
            set
            {
                _OrderCustomerName = value;
            }
        
        }
        
        public Order()
        {

            
        }

        
        
        public void Insert()
        {
            Customer Customer1 = new Customer();
            string OrderCustomerID;
            

        OrderCustomerID = Customer1.SelectCustomer(_OrderCustomerName);

            SqlConnection conn = new SqlConnection(@"server=home; integrated security = true; database = test");
            string sqlins = @"insert into testOrder(OrderID,Qty,Details,CusID)values('" + _OrderID + "','" + _Quantity + "','" + _OrderDetails + "','" + OrderCustomerID + "')";

            SqlCommand cmd = new SqlCommand(sqlins, conn);


            try
            {

                conn.Open();
                cmd.ExecuteNonQuery();
            }
            catch (SqlException ex)
            {

            }
            finally
            {

                conn.Close();
            }


        
        }
        
    }
}


protected void Button1_Click(object sender, EventArgs e)
    {
        TCO.Order order1 = new TCO.Order();

        order1.OrderID = TextBox1.Text;(order id)
        order1.Quantity = TextBox2.Text;(quntity)
        order1.OrderDetiails = TextBox3.Text;(order details)
        order1.OrderCustomerName = TextBox4.Text;(customer name)

        order1.Insert();

        GridView1.DataBind();
    }