X,Y : Value for x,y axes for all the graphs.
Z1 : Value of Z for the first graph
Z2 : Value of Z for the second graph
Z3 : Value of Z for the third graph
1. Open an empty figure by typing "figure" in the command window.
2. Click on the window like structure given above in the tool bar just below "Help" (you must have used to type title of the figure and all).
3. Now when you open it, then either you can see "Figure Palette", if yes then proceed to next 4, otherwise click on the Desktop, and select Figure Palette from there (same as you do to see command window, workspace etc).
4. There you can see "New Subplots", select 3D Axes as many as you want.
5. Now once you got three 3D axes on the figure, you can add data to them by right clicking the axes.
6. Hope it works.