尝试写&；将结果附加到文件中

我的（相当）简单的应用程序的下图下面是它的代码。我需要知道如何将comboBox1（位置）、comboBox2（药物）、textBox1（数量）和textBox2（日期）导出到CSV或Excel类型的文件中，以运行报告。我刚接触C#两周了，真的可以使用帮助，因为我已经在这部分工作了，具体来说，现在已经工作了大约一周了！

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace WindowsFormsApplication1
{
       public partial class Form1 : Form
        {
                public Form1()
                {
                    InitializeComponent();
                }
                private void button1_Click(object sender, EventArgs e)
                {
                }
                private void button2_Click(object sender, EventArgs e)
                {
                }
                private void button3_Click(object sender, EventArgs e)
                {
                    Application.Exit();
                }
                private void exitToolStripMenuItem_Click(object sender, EventArgs e)
                {
                    Application.Exit();
                }
                private void toolStripMenuItem1_Click(object sender, EventArgs e)
                {
                }
                private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
                {
                }
                private void dateTimePicker1_ValueChanged(object sender, EventArgs e)
                {
                    dateTimePicker1.CustomFormat = "dd/MM/yyyy";
                    dateTimePicker1.MinDate = DateTime.Today;
                    dateTimePicker1.MaxDate = DateTime.Today;
                }
                private void label4_Click(object sender, EventArgs e)
                {
                }
                private void textBox2_TextChanged(object sender, EventArgs e)
                {
                    textBox2.Text = DateTime.Now.ToString();
                }

        }
}][1]