Ok I got the XML File working but how i would store more then one schedule tasks in XML file as in above it can add 1 task at one time. What will be the looping condition?

Following is some of my code:
Code:
private void addBtn_Click(object sender, EventArgs e)
        {

            XmlTextWriter sch = null;
            sch = new XmlTextWriter(filename, null);
            sch.Formatting = Formatting.Indented;
            sch.Namespaces = false;



            if (subjTextbox.Text.Equals(""))
            {
                MessageBox.Show("Subject cannot be left Empty", "Subject");
            }
            else if (textFile.Text.Equals(""))
            {
                MessageBox.Show("File Name Needed", "File");
            }
            else
            {
                try
                {

                    date = new DateTime(dateTimePicker1.Value.Year, dateTimePicker1.Value.Month, dateTimePicker1.Value.Day, Convert.ToInt16(hr.Text), Convert.ToInt16(min.Text), 0);
                    if ((Convert.ToInt16(hr.Text))>=12)
                    {

                        lvt = new ListViewItem(new String[] { subjTextbox.Text, textFile.Text, date.ToString() +  "pm" });
                    }
                    else
                    {
                        lvt = new ListViewItem(new String[] { subjTextbox.Text, textFile.Text, date.ToString() +  "am" });
                    }

                }
                catch (Exception ex)
                {
                    MessageBox.Show("Hour and Min fields are empty", ex.Message);

                    return;
                }
                if (IsInCollection(lvt))
                {
                    MessageBox.Show("Duplicate");
                }
                else
                {
                   
                    scheduleListView.Items.Add(lvt);
                   
                }
               
                try
                {
                   
                    sch.WriteStartDocument();

                    sch.WriteStartElement("Schedules");

                    sch.WriteStartElement("Scheduler");
                    sch.WriteString(subjTextbox.Text);
                    sch.WriteEndElement();

                    sch.WriteStartElement("FileName");
                    sch.WriteString(textFile.Text);
                    sch.WriteEndElement();

                    sch.WriteStartElement("DateTime");
                    sch.WriteString(date.ToString());
                    sch.WriteEndElement();

                   

                    sch.WriteEndElement();
                    sch.Flush();
                }
                catch (Exception e1)
                {
                    MessageBox.Show(e1.ToString());

                }