C#

DateTime dt1 = DateTime.ParseExact("11:15:00", "hh:mm:ss", new DateTimeFormatInfo());
DateTime dt2 = DateTime.ParseExact("11:20:00", "hh:mm:ss", new DateTimeFormatInfo());

TimeSpan ts1 = dt1.Subtract(dt2);
Console.WriteLine(ts1.ToString());

private DateTime started;

public Form1() {
    InitializeComponent();
    started=DateTime.Now;
    timer.Tick += new EventHandler(timer1_Tick);
    timer.Interval = (1000) * (1);
    timer.Start();
}

private void timer1_Tick(object sender, EventArgs e) {
    DateTime now=DateTime.Now;
    label6.Text = "It is now "+now.ToString("HH:mm:ss");
    double seconds=now.Subtract(started).TotalSeconds;
    label7.Text = "which is "+seconds+" seconds since this form started.";
}

using System;
using System.Drawing;
using System.Windows.Forms;

public partial class FormLogIn : Form
{
    TextBox textBoxUserName;
    TextBox textBoxPassword;
    Button buttonLogIn;

    public FormLogIn()
    {
        InitializeComponent();
        SuspendLayout();

        // textBoxUserName
        textBoxUserName = new TextBox();
        textBoxUserName.Location = new Point(12, 12);

        // textBoxPassword
        textBoxPassword = new TextBox();
        textBoxPassword.Location = new Point(12, 38);
        textBoxPassword.UseSystemPasswordChar = true;

        // buttonLogIn
        buttonLogIn = new Button();
        buttonLogIn.Text = "Log In";
        buttonLogIn.Location = new Point(12, 64);
        buttonLogIn.Click += buttonLogIn_Click;

        // this
        MinimizeBox = false;
        MaximizeBox = false;
        FormBorderStyle = FormBorderStyle.FixedSingle;
        StartPosition = FormStartPosition.CenterScreen;
        Size = new Size(132, 132);
        Text = "Log In";
        AcceptButton = buttonLogIn;
        Controls.AddRange(new Control[] { textBoxUserName, textBoxPassword, buttonLogIn });

        ResumeLayout(false);
    }

    void buttonLogIn_Click(object sender, EventArgs e)
    {
        // Validate credentials etc

        Close();
    }
}