Spectogram - 3 -dimensional-plot?

Hello Community! I am trying to turn a two-dimensional output of a spectogram to a 3-dimensional plot. Here in this code, i am plotting a mesh, just for understanding myself, how it works. Read the comments btw! I already have the code, how to compute my stft, but for mesh i need to know, how to define the axis out of the paramters from stft. If necessary, i can post the whole code.

%Here i am defining the parameters for my fft.
% My sampling frequency is 44100 and the number of fft points i use is 4096

X=1:10; %Do not belong to the stft. Just using them for the mesh function 
Y=1:15;
Z = [];

% Here i would define the number of time segments 
for i = 1:length(X)

      % Here in this line, i want to compute my stft

      % How do i define the number of frequencies here?
      % What do i have to write here in the for-loop?
      for j = 1: length(Y)
          Z(j,i) = 1.0/(i*j);
      end
  end

mesh(X,Y,Z)