private void btnChoose_Click(object sender, EventArgs e)
{
  using (OpenFileDialog dialog = new OpenFileDialog())
  {
    dialog.Multiselect = true;
    if (dialog.ShowDialog() == DialogResult.OK)
    {
      try
      {
        this.tbFilePath.Text = dialog.FileName;
      }
      catch(Exception ex)
      {
        throw(ex);
      }
    }
  }

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms.Design;
using System.Windows.Forms;
namespace  Common
{
  class FolderDialog:FolderNameEditor
  {
    FolderBrowser fDialog = new FolderBrowser();
    public FolderDialog(){ }
    public DialogResult DisplayDialog()
    {
      return DisplayDialog("請選擇一個文件夾");
    }
    public DialogResult DisplayDialog(string description)
    {
      fDialog.Description = description;
      return fDialog.ShowDialog();
    }
    public string Path
    {
      get
      {
        return fDialog.DirectoryPath;
      }
    }
    ~FolderDialog()
    {
      fDialog.Dispose();
    }
  }
}

private void btnChoose_Click(object sender, EventArgs e)
{
  FolderDialog fDialog = new FolderDialog();
  fDialog.DisplayDialog();
  this.tbfilePath.Text = fDialog.Path;
}