Actually there is no need to Enter an “Unlock Code” on Apple iPhone, all the process is done via iTunes once you receive from us the confirmation of Unlock.
1 – Install the last version of iTunes
2 – Make sure your iPhone is updated with the lastest version of Firmware.
3 – Switch on your iPhone with a Not Accepted SIM Card
4 – Connect your iPhone to your computer using the Original USB Cable
5 – Launch iTunes & wait until iTunes detect your iPhone
6 – Now disconnect your iPhone and reconnect it after 10 seconds.
7 – Your iPhone is now Unlocked.