This is for all the people out there who are having trouble programming their key. I've tried many different ways suggested by members from this forum and Audiworld. I also googled but none of it works for me!! With the help from offroader1006 and 99.5A4, I was able to program my keys with a combination of their methods.

Instructions:
1) Spare Key in ignition (2 clicks)
2) Remote 1 in the door lock and lock it, let the key return to its normal position in the door lock.
3) With the key still in the lock, press and hold the lock button on the remote for several secs. Light flahes.
4) Let go of the lock button, wait a few secs, press the unlock button once while the key is still in the lock. Light flahses again and the door should unlock. (I repeat step4 one more time, but I don't know if its nessesary) Remote 1 is now programmed.
5) Remove all keys, standing outside the car, try to lock and unlock the car with the remote see it works.

Now if you want to program the second remote, don't repeat those steps!! cause I've tried and didn't work for me.

6) Remote 1 in ignition (2 clicks) (I don't know if spare key will do, I used remote 1 this time)
7) Remote 2 in the door lock and lock it, let the key return to its normal position in the door lock.
8) With the key still in the lock, press the unlock button twice. Light flahes twice. (I don't remember if the door unlock this time after pressing the unlock button twice, I think it didn't unlock)
9) Manually unlock the door.
10) Remove all keys, standing outside the car, try to lock and unlock the car with 2nd remote see it works.