Tim wants to know why he's not getting his phone updated. Leo says that since Tim is a subscriber of Straight Talk, it's likely that they aren't sending out all the official updates. Leo advises talking to Straight Talk about when he can expect the next update for his phone.
The only other option is to root it and install it himself, but that's not for everyone. He can find out how to do it at XDA Developer Forums. He'll have to follow the directions to the letter or he'll end up bricking his phone.