This is a very simple step to create Dialog with IronRuby. I assumed you get IronRuby and have ir.exe
1. run the IronRuby interactive console
C:\OpenSource\ironRuby\trunk\build\debug>ir.exe
2. create reference to Windows Forms namespace
>>> require 'C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.Windows.Forms.dll'
3. create global object to hold MessgeBox class
>>> $ironForm = System::Windows::Forms::MessageBox
4. call show dialog
>>> $ironForm.show 'Hello World IronRuby'