Custom short time spectral processing function and plotting continuous

    function [ Mag, Phase ] = magPhase( Frame )
  xF = Frame(1:320)*hamming(320);
  y = fft(xF);
  Mag = abs(y);
  Phase = angle(y);
  end

I am trying to input a speech, get 20ms frame from the speech and find the magnitude and time phrase of it. Is that seem to be correct at the current stage?

Furthermore, how to overlap 50% the frame of speech? And what does this mean?

For plotting continuous, how can I do that? For example, i make a for loop and value x will be plotted. Lets say, it ended at a, the next loop will assign a new value to x, I want the next plot starts from a instead of overwrite the figure

Thanks