Bliking a LED every 500ms

Hi, people I need some help,I do this code:

#include <msp430g2553.h>/*MCU */
#define LED_VERMELHA    BIT0
int SS = 0;
int main(void){
   WDTCTL = WDTPW + WDTHOLD;
P1DIR |= (LED_VERMELHA);
   P1OUT &= ~(LED_VERMELHA);


 if (CALBC1_1MHZ ==0xFF || CALDCO_1MHZ == 0xFF)
   BCSCTL1 = CALBC1_1MHZ;
   DCOCTL = CALDCO_1MHZ;

 TA0CCR0 = 65500;
   TA0CCTL0 = CCIE;
   TA0CTL = TASSEL_2 + MC_1 + ID_3;  
   _BIC_SR(GIE); /*ENABLE INTERRUPT*/


   while(1){
   }
}

#pragma vector=TIMER0_A0_VECTOR
   __interrupt void Timer_A(void) {	/*TIMER0_A0 INTERRUPT SERVICE ROUTINE*/

	SS++;
	P1OUT ^= LED_VERMELHA;

}

I would like to flash the LED every 500ms, but I can not make it work, can someone help me?