I'm guessing every time you unlock the car/open the door the alarm goes off?? This is due to a switch in the lock. Can be replaced quite easily, just a bit fiddly.
The quick fix is to just disconnect the horn, found in the boot! It's on the left hand side, behind the panneling. Just reach your hand down there, and pull off one of the wires.
To actually fix the problem, read on...
You can test the alarm. Close all doors, open bonnet. Key not needed in ign. Press the plunger for the bonnet sensor 8 times. The alarm system will give a little honk, to say it's in test mode. Go around all doors, and open 1 at a time. The horn should honk once if the item is ok. Put key in lock, and turn as if unlocking the car. You should get a honk, telling you the switch in the lock is ok. Now turn the other way as if to lock, and listen for a honk. if you don't get one somwhere you have a fault. the car will leave test mode with a honk after no input for several seconds.
The switch is actually on the lock barrel, on the inside. You'll need to remove the door panel, and most of the lock.
Rob
September 2006