How do i quantize data with N levels?

I have the following code and have to quantize Y with N=8 levels in the uniform quantizer. Can you help me about it? Thank you in advance.

close all; 
clear all; 
rand('seed', sum(100*clock));
x1 = 0 + (4-0) .* rand(1000000,1);
x2 = -2 + (0-(-2)) .* rand(1000000,1);
y=x1+x2;
ymeansquared=mean(y.^2);

Answer 1

[Scott MacKenzie]

y1 = discretize(y,8);