You don't say what make the alarm is but most of them have a small keyhole for a key to turn the alarm off which should have been supplied with the car.
Assuming that you don't have that key.  1)  Try a new battery in the fob.  2) Have the alarm stripped out by a specialist.  (If you don't know what you are doing you can completely immobilise the car.)
                
 t
                
 September 2008