After getting sufficiently well in your practice. You may also perform MulaBandha while holding the breath outside.

The practice of Mula bandha includes the contraction of some particular pelvic muscles. Not the contraction of the whole pelvis.

Males are ought to contract the muscles between anus and testes. Females need to contract the muscles behind the cervix. Cervix is the point where the lower end of the uterus projects into the vagina. It is the muscles surrounding Muladhara chakra that are meant to be contracted during Mulabandha.