Clean baby’s poo

Hi mummies, FTM here. Heard that its recommended to clean baby’s bum using water instead of wet tissue when baby poo unless if necessary or at night. If using water, when opening the diaper, how do you clean off the excess poo from baby’s bum first? And afterwhich you bring baby to toilet to clean using running water ? do we need soap or just water? #FTM #advicepls