How do I hack into a person's FB account for my friend?

[Arie]

You cannot hack into a Facebook account. If that would be possible, everyone would be doing it. There are no security flaws in Facebook at current. Your account has not been hacked either. What in fact happened is that you chose a weak password which was guessed, or your chose a weak secret question which was guessed, or you did not keep your operating system and applications up to date which led to a virus recording your password, or you were foolish enough to be tricked to log into a fake website which was made to look like Facebook, et cetera. You were however not hacked. Others therefore cannot help you with hacking into a Facebook account either.