Help required !!!

Hi Friends,
I've a requirement where in i've to provide an active dialogue box(modal dialogue) to the user to select one of the radio buttons provided in that. There will be two radion buttions and he has to select one, so that i've to get the value of that button and according to that i'll call a javascript function. so can anybody tell me for this problem how to come out of it!!!
i need both how to get the value in that form and how to rite a java script function there.

it wud b a great help for me!!!

venkat