Using Maple 11 for calculus problems

[MAins]

For a function f(x,y) what commands do I use to plot the coresponding surface from, say, -2 </= x, y </= 2? How would I then plot contours?

 

[benorin]

For the example I have chosen $$f(x,y)=\frac{x}{\sqrt{1+x^2+y^2}}$$.

restart;
with(plots);
f:=(x,y)->x/(1+x^2+y^2)^(1/2);
plot3d(f(x,y),x=-2..2,y=-2..2);
contourplot(f(x,y),x=-2..2,y=-2..2,contours=25);