Kim,From the diaphragm, the midriff, the gut: lower than the lungs. Sing from there, too. Breathe in, trying to get the air down there; the lungs will fill by themselves (an old habit they have). Much more control, methinks. It helps if you stand up to do this, but you may find that it changes "your key" somewhat, usually lowering it.
My high school choir teacher was a class A jerk, but at least he gave me that.
Sarah