private void btnAdd_Click(object sender, EventArgs e)
        {
            if (openFileDialog1.ShowDialog() == DialogResult.OK)
            {
                try
                {
                    string[] arr = openFileDialog1.FileNames;
                    alAttachments = new ArrayList();
                    txtAttachments.Text = string.Empty;
                    alAttachments.AddRange(arr);

                    foreach (string s in alAttachments)
                    {
                        txtAttachments.Text += s + "; ";
                    }
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.Message, "Error");
                }
            }
        }

txtAttachments.Text = Path.GetFileName(openFileDialog1.FileNames)

string[] arr = Path.GetFileName(openFileDialog1.FileNames);

        private void radButton2_Click(object sender, EventArgs e)
        {
            foreach (string fullPath in ma.AttachmentFileName)
            {
                File.Delete(fullPath);
            }
        }