How does Crescent Jacob become a werewolf?

You can find the answer in the original text.

1. That's because his temperature is rising and he is very upset (Mike Newton was there at that time).

He became like that because there is a rule of keeping secrets in the population to protect his identity. Werewolves have a bad temper and can't control themselves. He was afraid of attacking Bella herself.

3. Similarly, because werewolves are grumpy and can't control themselves, Bella blames them for making Jacob's temperament change greatly, so she slaps him (the name is inaccurate) and turns him into a character.

Indeed, this is an ancient legend, and he once regarded her as a joke.

5. Because every time a vampire is added to the town, a child with werewolf blood will change.

I suggest you read the original, so there won't be so much confusion.

Although the original book is very long and not as interesting as the movie, the movie omits many details because of time constraints.