Going into a foster home? ~read?

I have a few questions about this. If a child or mid teen can no longer live with their family are they able to be put in a foster home? How would they do that? If a child wants to be put into a foster home but the parents object, can they go? If so, how? If they go, are they able to choose a family? Maybe a family friend or a friends mom? And how does it work? Like miss honey signed a paper from matildas parents?