another 3D question - basic

Hi all,
have just started making the transition from 2D-3D in cad, most things are
going well and ive drawn a few models, but still missing some of the basic
points.....


if i draw, say, a square as a polyline, with a circle inside it, then use
the region command, then extrude them both into the z axis, how do i get the
circle to become a void rather than a solid? or am i going about this in
totally the wrong way? How do i cut a hole in my solid once its drawn?

really wish my company would buy solidworks :-(

Thanks,
Shaun

 

don't region them. extrude them first, then subtract, you may also want to
experiment with the slice command for cutting solid with a straight plane