Maria,

Try this code in your program:

while(1)
{
while(SWITCH) //Switch pressed
{
LED=1; //Turn on LED
delay1sec();
LED=0 ; //Turn off LED
delay1sec();
}
BUZZER=1; //Turn off BUZZER
BUZZER=0; //Turn on BUZZER
}

Don't forget about the switch debouncing.

Regards,
George