Hello,
normaly you have to remove a diffusor before you can see the screws of the carrier bracket.
That's no big problem, the diffusor is only locked with some "clips".
Remove it, and you can see the Screw Heads from the bottom of your car. Should be a big torx not a inbus (the inbus is only for adjusting the hight of the Bumper).
But before removing the bumper you should remove the screws in the fenders. There are 3 Screws or Expanding rivet to remove.
When these Screws are removes you can take the bumper with one person off. Just pulling to the back of the car :-))
It's not a heavy thing, but be carefull or your lacquer would b screwed up :-))
A nice explanation you can find here.(it's for removing a trailer coupling, but it helps for your work).
http://rapidshare.com/files/21185825/E36_-_Anhaengervorrichtung.pdf