How do you get the zombie maps for black ops?

The first map you get for free.

Theres one map which is an arcade... So if you want to do the arcade (This only works for 360 I'm not sure for PS3 possibly the big buttons at the back, on Xbox when you'r in the chair at the main menu, keep pressing RT and LT together untill you go free from the chair. When you'r out go behind and there's a PC you need a password you can get the password from Googling it.

The other map is in the pentagon and you unlock it by completing the story mission on blackops!How do you get the zombie maps for black ops?
Beat the game or at the menu selection screen push the r1L1 or r2L2 a couple times. Mason will get out of the chair. Walk over to the computer and type in 3arc unlock