rpm -Uvh mono-posix-0.91-0.ximian.6.3.i386.rpm \ mono-core-0.91-0.ximian.6.3.i386.rpm

$ mcs --about
The Mono C# compiler is (C) 2001, 2002, 2003 Ximian, Inc.
 
The compiler source code is released under the terms of the GNU GPL
 
For more information on Mono, visit the project Web site
   http://www.go-mono.com
 
The compiler was written by Miguel de Icaza, Ravi Pratap and Martin Baulig

[HelloWorld.cs]
using System;

public class HelloWorld
{
  public static void Main()
  {
    Console.WriteLine( "Hello, world!" );
  }
}

$ mcs HelloWorld.cs
Compilation succeeded

$ mono HelloWorld.exe
Hello, world!

[WinForms.cs]
using System;
using System.Drawing;
using System.Windows.Forms;

public class Test : Form
{
  private Button button;
  private CheckBox checkBox;
  private RadioButton radioButton;
  private Label label;
  private PictureBox pictureBox;

  public Test()
  {
    this.ClientSize = new Size( 640, 480 );
    this.Text = "Windows forms";

    button = new Button();
    button.Location = new Point( 10, 10 );
    button.Size = new Size( 100, 25 );
    button.Text = "Click me";
    button.Click += new EventHandler( Button_Click );

    label = new Label();
    label.Location = new Point( 10, 40 );
    label.Size = new Size( 200, 20 );
    label.Text = "Windows Forms";

    radioButton = new RadioButton();
    radioButton.Location = new Point( 300, 10 );
    radioButton.Size = new Size( 200, 20 ); 
    radioButton.Text = "Radio button";
    radioButton.Checked = true;

    checkBox = new CheckBox();
    checkBox.Location = new Point( 300, 50 );
    checkBox.Size = new Size( 200, 20 );
    checkBox.Text = "Check box";
    checkBox.Checked = true;

    pictureBox = new PictureBox();
    pictureBox.Location = new Point( 30, 120 );
    pictureBox.Size = new Size( 240, 180 );
    pictureBox.Paint += new PaintEventHandler( PictureBox_Paint );

    Controls.AddRange( new Control[]
      {
        button,
        label,
        radioButton,
        checkBox,
        pictureBox
      }
      );
  }

  public static void Main()
  {
    Application.Run( new Test() );
  }

  private void Button_Click( object sender, EventArgs e )
  {
    MessageBox.Show( "clicked", "test" );
  }

  private void PictureBox_Paint( object sender, PaintEventArgs e )
  {
    e.Graphics.DrawRectangle( Pens.Red, new Rectangle( 10, 10, 50, 50 ) );

    e.Graphics.DrawRectangle( Pens.Blue, new Rectangle( 40, 40, 120, 80 ) );

    e.Graphics.DrawString( "Windows forms", Control.DefaultFont,
                             Brushes.Green, new PointF( 30.0f, 20.0f ) );
  }
}

$ mcs -r:System.Windows.Forms -r:System.Drawing WinForms.cs
Compilation succeeded
$ mono WinForms.exe