add matrix data for plotting in 3D including 2D

i am searching for good coder about mix my data matrix for plotting like this

[X,Y,Z] = peaks(25);
surfc(X,Y,Z)
hold on
hAx(1)=gca;
pos=hAx(1).Position;
wh=diff(reshape(pos,2,[]).'); w=wh(1); h=wh(2);
l=pos(1); b=pos(2);
T=0.95; R=0.75;
hAx(2)=axes('Position',[l+T*w b+T*h (1-R)*w (1-R)*h],'Color','none');
hL=plot(hAx(2),X(ceil(25/2),:),Z(ceil(25/2),:),'k-','linewidth',2);

also my ploting data is like this

data = load('ST1.txt');

Error using load
Unable to find file or directory 'ST1.txt'.

core = reshape(data(:, 3),100,100).';
subplot(3,1,1)
surf(real(core),'edgecolor', 'none')
subplot(3,1,2)
surf(imag(core),'edgecolor', 'none')
subplot(3,1,3)

surf(abs(core),'edgecolor', 'none')

i want to plotting like graph 1 by using data matrix file ST1.txt ?