CIN 3 and CIN 2 Biopsy results

I got a call from my doctor and she recommends to do a LEEP as they discovered CIN 3 and CIN 2. last 6 months it was just CIN 2.

what should I do to prepare? Is it painful? And post surgery what should I do? And is it totally gone after that? Or tips that it won’t re-occur again?

Thank you for any information please.