Hide form2 when main form is hide also in startup

See more:

C#

Windows

form

I have a small project about manage time use on computer.
Form1:

public partial class Form1 : Form
{
    private Timer t = new Timer();
    public static int counter = 60;
    public Form1()
    {
        InitializeComponent();
        t.Tick += new EventHandler(Timer_Tick);
        t.Interval = 1000;
        t.Enabled = true;                       
        t.Start();
        Form2 TheForm2 = new Form2();
        TheForm2.ShowDialog();
    }

    void Timer_Tick(object sender, EventArgs e)
    {
        counter -= 1;
        if (counter==20)
        {
            MessageBox.Show("Time remaining "+counter.ToString());
        }

    }
}

And Form2:

public partial class Form2 : Form
{
    public Form2()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        int userVal = int.Parse(textBox2.Text);
        Form1.counter += userVal;
    }

    private void textBox2_TextChanged(object sender, EventArgs e)
    {

    }

    private void button2_Click(object sender, EventArgs e)
    {
        textBox1.Text = Form1.counter.ToString();
    }

    private void textBox1_TextChanged(object sender, EventArgs e)
    {

    }
}

Final program:

static class Program
{
    /// <summary>
    /// The main entry point for the application.
    /// </summary>
    [STAThread]
    static void Main()
    {
        Application.EnableVisualStyles();
        Application.SetCompatibleTextRenderingDefault(false);
        Form1 TheForm = new Form1();
        Application.Run();
    }
}

What I have tried:

I try to make this application run on Windows start up and the Form1 is hide. But I wanna make form2 invisible also. And it just show when user excute the application. How can I solve it? I just put this exe to folder start up to make it run on start.(I'll try to make it with Registry)