in addition to the capacitor there should also be a resistor from the pin 9 to ground. say a 10K resistor....while you place a capacitor from the Vdd to the reset pin also.
the positive terminal of the capacitor should be connected to Vdd while the negative terminal should be connected to the reset pin
hope this helps...
sequel
Dear Friend..
Just make simple connection like given circuit....
=> In this connection Initially 5V goes to GND.. But when you press switch 5V appears of RESET pin of 89s52..