Go to this website to sign up.
http://www.collegeboard.com/testing/
When you register, you can also select so that they send you daily SAT questions for you to practise. The new format got essay component, diff from last time's SAT. So if you plan to buy or borrow any guidebooks, you should probably look for the newer ones that include the essay component. SAT can learn to be exam smart and score full marks de, so, that is what those guidebooks do; they teach you to be exam smart for SATs. But personally, I heck care and just do the daily questions nia. Essay component is basically like AQ for GP.