How do I replace a floor flange on a toilet?

Screendean...

I can tell you how to replace flange... but tell me what kind of flange... cast iron or plastic with metal or plastic ring?

Also, why are you replacing it? If just because one side has broken off then they make a spanner flange for exactly that situation... see pictures below. First pic. Is for pvc flanges... second picture is for repairing cast iron flanges... slips under old flange.

Otherwise answer my questions and I will post back later to explain all that I can.

MARK

I guess what Mark and I are both thinking is the why part. If we knew why we could give a much more precise answer, most flanges do not need to be removed.