access data in textfied in gridview

im working on a shopping cart i have a gridview that loop throuh all record in the database and display on the gridview i add two extra column one for a link when user click on the link it add the product in the shopping cart the other column is a textfield which user should enter the quantity of the item they want to purchase here is my problem i can get the value user enter in the textfield can someone please give me some direction thank you

Aspx page

<asp:GridView ID="grdProducts" runat="server">

  开发者_C百科          <Columns>
                <asp:ButtonField CommandName="AddToCart" HeaderText="Add To Cart" Text="Add To Cart" />

              <asp:TemplateField HeaderText="Qty">
            <ItemTemplate>
                <asp:TextBox ID="tbQty" runat="server" Width="25px"
                    MaxLength="3" />
                    </ItemTemplate>
                        <ItemStyle Width="25px" HorizontalAlign="Center"/>
                            </asp:TemplateField>


            </Columns>


        </asp:GridView>

Code behind the page

 Private Sub grdProducts_RowCommand(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewCommandEventArgs) Handles grdProducts.RowCommand

        Dim intRowSelected As Integer = -1
        Dim strProductName As String = ""

        Try

            intRowSelected = e.CommandArgument
            strProductName = grdProducts.Rows(e.CommandArgument).Cells(2).Text
            AddItemToCart(strProductName)



            Dim rowIndex As Integer

            If Integer.TryParse(e.CommandArgument.ToString(), rowIndex) Then

                Dim c As Control = grdProducts.Rows(rowIndex).FindControl("tbQty")
                If TypeOf c Is TextBox Then
                    Response.Write(DirectCast(c, TextBox).Text)
                    PlaceHolder1.Controls.Add(c)
                End If
            End If


        Catch ex As Exception
            Debug.WriteLine(ex.Message)
        End Try

    End Sub

how can i fetch data in (textfield id =tbQty)

http://aspdotnet-example.blogspot.com/2011/04/gridview-data-control-in-aspnet-example.html

in that GridView.ASPX.cs page give you result