怎样在发件箱的内容部分实现文字格式功能？

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="sendDoc.aspx.cs" Inherits="document_sendDoc" %><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>无标题页</title>
    <link rel="stylesheet" type="text/css" href="../CSS/CSS.css" />
</head>
<body style="background-image: url(../image/rightFrame.gif)">
    <form id="form1" runat="server">
    <div>
        <br />
        <br />
        <br />
        <br />
        <br />
        <br />
        <br />
        <table style="width: 675px; height: 200px" class="css" border="1" align ="center">
            <tr>
                <td align="center" colspan="3" class="cssTitle">
                    公文传送</td>
            </tr>
            <tr>
                <td style="width: 64px">
                    审批人：</td>
                <td colspan="2">
                    <asp:DropDownList ID="ddlName" runat="server" Width="154px" CssClass="InputCss">
                    </asp:DropDownList></td>
            </tr>
            <tr>
                <td style="width: 64px">
                    标题：</td>
                <td colspan="2">
                    <asp:TextBox ID="TextBox1" runat="server" Width="516px" CssClass="InputCss"></asp:TextBox><asp:RequiredFieldValidator
                        ID="RequiredFieldValidator1" runat="server" ControlToValidate="TextBox1" ErrorMessage="**　必填项"></asp:RequiredFieldValidator></td>
            </tr>
           <tr>
                <td style="width: 64px; height: 14px">
                    内容：</td>
                <td style="height: 14px;" colspan="2">
                    <asp:TextBox ID="TextBox2" runat="server" Height="109px" TextMode="MultiLine" Width="517px" CssClass="InputCss"></asp:TextBox><asp:RequiredFieldValidator
                        ID="RequiredFieldValidator2" runat="server" ControlToValidate="TextBox2" ErrorMessage="**　必填项"></asp:RequiredFieldValidator></td>
            </tr>
            <tr>
                <td style="width: 64px; height: 21px">
                    附件：</td>
                <td colspan="2" style="height: 21px">
                    上传的文件不可以超过4M<br />
                    <input id="File1" style="width: 589px" type="file" runat="server" class="InputCss" /></td>
            </tr>
            <tr>
                <td align="center" colspan="3">
                    <asp:Button ID="btnSend" runat="server" Text="发　送" Width="72px" OnClick="btnSend_Click" CssClass="redButtonCss" />
                    <asp:Button ID="Button2" runat="server" CausesValidation="False" Text="重　置" Width="72px" CssClass="redButtonCss" OnClick="Button2_Click" /></td>
            </tr>
        </table>
    
    </div>
    </form>
</body>
</html>提问：怎样在代码——
           <tr>
                <td style="width: 64px; height: 14px">
                    内容：</td>
                <td style="height: 14px;" colspan="2">
                    <asp:TextBox ID="TextBox2" runat="server" Height="109px" TextMode="MultiLine" Width="517px" CssClass="InputCss"></asp:TextBox><asp:RequiredFieldValidator
                        ID="RequiredFieldValidator2" runat="server" ControlToValidate="TextBox2" ErrorMessage="**　必填项"></asp:RequiredFieldValidator></td>
            </tr>中加入一些代码，使其实现文字格式（如字体选择、字体选择、字体颜色等）功能？