Boy, are you about to get an education. Welcome to Free Republic.
According to the immigration and naturalization statutes which were in effect at the time of Obama's birth, his mother was not old enough to convey legal US citizenship to him UNLESS she gave birth to him within the territorial jurisdiction of the United States.
If she gave birth to Obama outside of the US, then he's not a US citizen, much less, a Natural Born Citizen (as required by the US Constitution).
LoL. No kidding. Welcome to FR, CC.
For a great analysis as to why simply being "a citizen" is not enough to qualify as a Natural Born Citizen eligible to hold the office of the presidency, read the following excellent piece put together by fellow FReeper, Sourcery.
http://www.freerepublic.com/focus/f-news/2840767/posts
It's all about presumed loyalty.