Sorry, annfan, but it is you who have no clue. The following "yardstick" is Article 2, Section 1, Paragraph 5 of the Constitution of the United States of America. Perhaps you've heard of it?
"No person except a nautral born Citizen, of a Citizen of the United States, at the time of the Adoption of this Constitution, shall be eligible to the Office of President: neither shall any Peron be eligible to that Office who shall not have attained to the Age of Thirty-five Years, and been fourteen Years a Resident within the United States."
Is that enough of a "yardstick" for you?