How to generate a signal with zero mean and 0.2 variance (uniform)

I was wondering how to generate this signal, and to mix it with xn that I already made:

   n = [0:1023];
  omega = 0.25*pi;
  xn = sin(omega*n);
  plot(n,xn);

I also need to find the SNR of the combined signal and plot the magnitude spectrum if possible.

Answer 1

[Matt J]

Some useful commands: randn, fft, abs, angle