The point spread works like this:
You have San Diego v New York, San Diego favoured by 6.5
You choose San Diego. In order for you to win, San Diego must win by 6.5 points or more (so, 7 or more). If San Diego wins by 6 or less, or if they lose, you lose.
You choose New York. In order for you to win, New York must win, or if they lose, they can lose by no more than 6 points.
No tie issues within 3 points. That's only Pro Line.
But it looks like everything's been answered anyways...