hii iam sry i have put this Question in another thread becuase i m still new i actaully didnot see that theris a thread for tutorials Qs

anyway iam still a newby in maya and i have started doing the frankestine tutorial ,,its that i have stopped where he says (use SUBD to smooth your geometry ,,,SUBDs are great)
but the problem is that i couldnot use the SUBd at all neither on poly or nurbs or anything it just wont accept using it on my model ,,can anyone help me at tell me why especially cuz at ths point if i dont smooth it in such a good way then its over it doesnot look good !!!1