วนลูปสร้าง Textbox ค่ะ แต่ต้องการใส่ในส่วนของปฏิทิน และกำหนด Css รบกวนหน่อยคะ

 List<TextBox> ArrayTextBox; 
        int num =Convert.ToInt32(TextBox1.Text);
        ArrayTextBox = new List<TextBox>();
        for (int i = 0; i < num; i++)
        {
            TextBox tb1 = new TextBox();
            tb1.ID = "TextBox" + i.ToString();
            ArrayTextBox.Add(tb1);

            RequiredFieldValidator aRequiredFieldValidator = new RequiredFieldValidator();
            aRequiredFieldValidator.ControlToValidate = "TextBox" + i.ToString();
            

            PlaceHolder1.Controls.Add(aTextBox);
            PlaceHolder1.Controls.Add(new LiteralControl(@"<br />"));


        }

<asp:TextBox ID="txt_date_book" runat="server" CssClass="textreadrr_green" 
                                Width="80px"></asp:TextBox>
                            <cc1:CalendarExtender ID="TextBox1_CalendarExtender" runat="server" 
                                Enabled="True" TargetControlID="txt_date_book" Format="dd/MM/yyyy">
                            </cc1:CalendarExtender>
                            <cc1:MaskedEditExtender ID="txt_date_book_MaskedEditExtender" runat="server" 
                        Mask="99/99/9999"
                        MaskType="Date "
                        MessageValidatorTip="true"  
                        OnFocusCssClass="MaskedEditFocus" 
                        OnInvalidCssClass="MaskedEditError"
                        CultureAMPMPlaceholder="" CultureCurrencySymbolPlaceholder="" 
                        CultureDateFormat="" CultureDatePlaceholder="" CultureDecimalPlaceholder="" 
                        CultureThousandsPlaceholder="" CultureTimePlaceholder="" Enabled="True" 
                        TargetControlID="txt_date_book">
                    </cc1:MaskedEditExtender>