On Facebook you can block people and you can set your account to private so no one can see any of your information unless you add them. You can also make it so that only you can add people, so random people don't go adding you.
Fanpop is safe but there is no real privacy settings, everything, even your club activity is public.
You don't have to give your real name or upload your own photos on Facebook either. I do however because my Facebook is strictly family and friends I know in real life only.