Can Any One Tell Me How To Program A Key Fob With Central Locking On It For 2000 X

At 2000, your BMW should have it's remote built into the key, not as a separate fob.
The procedure is;
Unlock the vehicle using the remote
Enter Vehicle
Close Driver's Door
Switch ignition ON the OFF
Press & hold the UNLOCK button
Press LOCK button 3 times within 10 seconds whilst holding unlock button down.
Release unlock button
Some models will then flash the LED in the key or rapidly lock & unlock the doors to show completion.
Other models may need you to repeat the entire procedure once more.
The later type remote keys with a BMW badge in the centre can be programmed by inserting into the ignition & turning on, then off.

At 2000, your BMW should have it's remote built into the key, not as a separate fob.
The procedure is;
Unlock the vehicle using the remote
Enter Vehicle
Close Driver's Door
Switch ignition ON the OFF
Press & hold the UNLOCK button
Press LOCK button 3 times within 10 seconds whilst holding unlock button down.
Release unlock button
Some models will then flash the LED in the key or rapidly lock & unlock the doors to show completion.
Other models may need you to repeat the entire procedure once more.
The later type remote keys with a BMW badge in the centre can be programmed by inserting into the ignition & turning on, then off.