Thanks, that does make sense. I guess confusion arises as the leading edge is actually to the rear of the bike.
See this:
So the pads need to be closer to the rim at the end of the pads that is nearest the
front of the bike.
As you pull on the brakes, the rim tries to drag the brake pad along with it, and this twists it (about an axis coming out of the screen, as you look at this diagram). This brings the rest of the pad into contact with the rim.
If you toe-in the other end, the rim still tries to pull the pad along with it, and this time the twisting is in the opposite direction, so the left end of the pad (in the diagram) tries to dig further into the rim and judders along - this is what can make them squeal.
A whole page on brake advice
here (just search that site if these aren't the same kind of brakes.
And if you haven't yet come across the fount of all knowledge:
http://sheldonbrown.com/
(don't let the basic web design put you off!)
Edited to add the missing link!