calculate remaining time from current date to selected date

calculate remaining time from current date to selected date and display the result on a label.In my design section i have 1 text box with a calender control and 1 button to submit the selected date in database and 1 label which shows the remaining days .
 below is my code.
/*********************************************************/
using MySql.Data.MySqlClient;
using System.Windows.Forms;
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{

}
protected void Button1_Click(object sender, EventArgs e)
{
Calendar1.Visible = true;
}
protected void Calendar1_SelectionChanged(object sender, EventArgs e)
{
txtdate.Text = Calendar1.SelectedDate.ToShortDateString();
Calendar1.Visible = false;
}
protected void Button2_Click(object sender, EventArgs e)
{
try
{
string MyConnection2 = "datasource=localhost;port=***;username=***;password=***;DATABASE=ts";
string Query4 = "insert into ts1(DATESELECTED,CURRENTDATE) values('" + this.txtdate.Text + "',NOW());";
DateTime.Now.ToString("dd-MM-yyyy ");
MySqlConnection MyConn2 = new MySqlConnection(MyConnection2);
MySqlCommand MyCommand2 = new MySqlCommand(Query4, MyConn2);
MySqlDataReader MyReader2;
MyConn2.Open();
MyReader2 = MyCommand2.ExecuteReader(); // Here our query will be executed and data saved into the database.
MessageBox.Show("Save Data");
while (MyReader2.Read())
{
}
MyConn2.Close();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
}


please suggest ASAP