How does a woman become a man?
First of all a man doesn’t become a woman & a woman doesn’t become a man. A transgender woman was always a woman, regardless of her body before surgery & a transgender man was always a man, even when he was in a female body. The way phalloplasty surgery works is strange. They use the genital tissue that they can to construct the head & glans of the penis for sensation & usually take a graft of skin from the forearm or the inner thigh to make the shaft. The results are nowhere near as natural looking & sophisticated as vaginoplasty is & a lot of transmen decide not to have phalloplasty for that reason.