The reason I, or no one hasn't gone into great detail about this is that basically, there is a bit to it.
Draw you attention to the rear (wheels) adjustment of the handbrake when you can't get enough out of the front (handbrake lever) adjustment.
If someone can be bothered copying what the holden workshop manual says about adjusting the handbrake, it will help this man in a big way. (i don't know how to do that with PDF)
You have to release the handbrake, then back off the nut a bit, but there's a bracket in the way, so you will need to use a long 10mm socket, or not fully lock in your ratchet (breaker bar fits better) into the socket and do it that way. you then tighten it to 2nm of torque it says. Don't have a torque wrench or have any idea what that feels like, so it also says that a correctly adjusted handbrake will have 15 - 20mm of thread protruding from the nut.
My car has done over 200,000 km so it is more like 20 - 30mm.
Otherwise, check that the cables are in tact, not snapped (foul play?), they join from 2 seperate cables to 1 about mid way through the length of the car, in the middle, and then disappear into the body.