Q: Can't buy books!!!

I want to use my iBooks on my iPhone 4S to buy some books to read. But sadly all I can get are the old books from e.g. Jane Austine or Edgar Allen Poe. I have been trying my best to understand the situation but nothing helps. I would like to know whether or not my region (I am from Macau) actually has any access to iBooks store that I can actually buy books like the Hunger Games or Twilight. I am so frustrated because if this really happens, Apple is not doing a very good job of SELLING THEIR PRODUCTS. I don't mind paying the money. In fact I have also bought apps on the apps store and it went well... But just iBooks is bothering me, and I want to know why.

Problems:

1. Can't find any books on "Store", not to mention to buy them in the first place.

2. When I am trying to change my region to USA, I can't process to the next step because I don't live there and I neither have an address to provide, nor do I have a credit card over there, which, also brings out the problem that APPLE needs to change the policy of having an APPLE ID without the requirement of entering any information for the CREDIT CARD!

Any answer is appreciated. Thanks!