convert from sting to date

protected void AddButton_Click(object sender, EventArgs e)

 {

      int rowsaffected = MainTable.InsertIntoMainTable(int.Parse(DistDropDownList.SelectedValue), myDate, int.Parse(DiseaseDropDownList.SelectedValue), int.Parse(CasesTextBox.Text), int.Parse(GovDropDownList.SelectedValue));

       

        if (rowsaffected > 0)

        {

            ResultLabel.Text = "New Row Added";

        }

        else

        {

            ResultLabel.Text = "No Rows Added";

        }

    }