How to write Urdu on C# Controls...its urgent

Thanks,

Actually i have to write urdu on the controls, dynamically. But when i write urdu on the controls it dosn't joins the the characters, as it does in the richtextbox control of C#. In the richtextbox control i only provide the unicode of the urdu character and it automatically joins the characters according to the position of the character in the word. Is there any such class or function in C# that joins the characters according to their position in the word as the richtextbox does.