How do you unlock guns in black ops zombies?

Answer 1

All you need to do is simply make the money by killing Zombies in-game. Then you can walk up to the drawing or upgrade on the wall, and press the button displayed on the screen. The Random Box will give you a random gun, hence the name, that could be good or bad. It is worth it to take the risk of using the random box in order to get the ray gun or other powerful weapons.