รบกวนสอบถามปัญหาในการ เปิด-ปิดฟอร์มเอง ไม่ได้ c# จะต้องทำอย่างไรครับ

using System;
using System.Linq;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlServerCe;
using System.Data.SqlTypes;

namespace WindowsFormsApplication
{
    public partial class frmAdd : Form
    {
    
        public frmAdd()
        {
            InitializeComponent();
        }

// อินพุทค่าลงใน textbox แต่ละช่องก่อนทำการส่งไปยัง database

        private void btnAdd_Click(object sender, EventArgs e)
        {
            if (string.IsNullOrEmpty(this.txtID.Text))
            {
                MessageBox.Show("Please input (ID)");
                this.txtID.Focus();
                return;
            }

            if (string.IsNullOrEmpty(this.txtName.Text))
            {
                MessageBox.Show("Please input (Name)");
                this.txtName.Focus();
                return;
            }

            if (string.IsNullOrEmpty(this.txtUnit.Text))
            {
                MessageBox.Show("Please input (Unit)");
                this.txtUnit.Focus();
                return;
            }

            if (string.IsNullOrEmpty(this.txtLocation.Text))
            {
                MessageBox.Show("Please input (Location)");
                this.txtLocation.Focus();
                return;
            }

            if (string.IsNullOrEmpty(this.txtDate.Text))
            {
                MessageBox.Show("Please input (Date)");
                this.txtDate.Focus();
                return;
            }

            SqlCeConnection myConnection = default(SqlCeConnection);
            //myConnection = new SqlCeConnection("Data Source =" + (System.IO.Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().GetName().CodeBase) + "\\AppDatabase1.sdf;"));
            myConnection = new SqlCeConnection("Data Source =C:\\Users\\Nick\\Documents\\Visual Studio 2010\\Projects\\Present\\KIKI\\WindowsFormsApplication\\Database1.sdf;");
            myConnection.Open();
            SqlCeCommand myCommand = myConnection.CreateCommand();
            myCommand.CommandText = "INSERT INTO [mytable] ([ID], [Name], [Unit], [Location], [Date]) VALUES  " + " ('" + this.txtID.Text + "','" + this.txtName.Text + "','" + this.txtUnit.Text + "','" + this.txtLocation.Text + "','" + this.txtDate.Text + "') ";
            myCommand.CommandType = CommandType.Text;
            myCommand.ExecuteNonQuery();
            myConnection.Close();
          
            MessageBox.Show("Save Successfully");

            this.Hide();
            frmHome f = new frmHome();
            f.Show();
        }

        private void btnExit_Click(object sender, EventArgs e)
        {
            this.Close();
        }

        private void frmAdd_Load(object sender, EventArgs e)
        {

        }

    }
}