To plot the data just pass the plot matrices or vectors of x, y, and z data in parentheses: (X,Y,Z).
Mathcad can draw the surface, color it, put contours on it. What it can't do is number or label the contours (this is possible on a pure contour plot, but not when the contours are on a surface), and you can only set the number of contours, not the contour spacing.
Richard