How to Plot 3D surface

hello I have excel sheel has three columns, xyz, I wanna import the data and plot z(surface) based on the mesh xy. how can I do it? I tried to write a code as in pic

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%  excel sheet has 3 columns as below 
%        x   Y     z  
%        -   -     -  
%        -   -     -
%        -   -     -
%        -   -     -
% how to plot Z as surfece on mesh XY ?
% 
%********** IMPORT FILE FROM XLS SHEET***************%
filename = 'num.xlsx';
sheet = 1;
xlRange = 'A1:B1:C100';%%we can use another column insted of C 
subsetA = xlsread(filename, sheet, xlRange);

%%ZZ=reshape(subsetA(:,100),100,100) %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

[X,Y] = meshgrid(0:0.15:20,0:0.15:20); Z=reshape(X,Y,Z); %H = h.reshape(10,1); surf(X,Y,Z) %%%%%%%%%%%%%%%%%%%%%%%%

thx