Hi Paki,
the easiest really is using conditional formatting. Double click the control you want to hide/show and select contditional formating.
The select form the first dorpdownlist your radioButtonControl, in the second is not equal to and in the third "1" or "2" or Yes/No depending how you have set up your radion button.
If you want to use code you can get a reference to your radion button control like this:
IXMLDOMNode myRadioButton = thisXDocument.Dom.SelectSingleNode("my:myFields/my:RadioButtonControlName");
and then use
if(myRadioButton.text == "depending on how you have set the values to your radio button)
Listen to Motörhead cos they play Rock'n Roll :)