actually, using those three written examples, it possible to give a decent enough how-to
first, you’re going to want to use the Move command… (this command will temporarily disable the gumball if you’re using the gumball)
the Move command works pretty much the same way as the move tool in sketchup… pick a point on the object you’d like to move then click on a second point where you’d like to move it to…
if you want to snap to an endpoint in rhino then make sure you have the End snap turned on in the osnap panel.
to stack cubes, run the Move command, click on a bottom corner (or midpoint or whatever) of the cube you’d like to stack then click again at the corresponding upper corner of the cube you’d like to stack on top of
to stack concentric cylinders make sure you have the osnap ‘Center’ enabled… run the Move command… hover your mouse over the bottom edge of the cylinder you’d like to move until you get a center snap… click the mouse… do the same thing on the top edge of the other cylinder and click when you get a center snap… they’ll be stacked perfectly concentric…
(hmm. does anyone know of a video lesson or something which shows this type of stuff in rhino? probably easier to explain that way instead of with words… or my words at least 
)
[Edit- oh. just saw your latest post… some of that 
may or may not apply]