I'm from the Turks and Caicos Islands and i use to sign in on my ipod but now i want to log in using my mac and it wont allow me to?

Facetime will not work if you do not have the correct date and time set on your mac or any other device using Facetime. If you can not set the date and time automatcally, you should be able to do it manualy. It is imperitive to have your time zone set correctly. Your time zone IS available on your Mac, I suggest lining up your time zone with a known city in South America that corresponds with your location. Also, if you want to try setting your time zone automatically, you must have the wifi in your mac computer turned on to do that.