Visit the "Test Dates" page of the official College Board website.
Scroll to the desired test date. Click on the "Register Now" link, located in the "Register" column.
Press the "Sign Up" button. Enter your personal information, desired username and password and press the "Submit" button.
Fill out your payment and school information, on the "Register" page. Highlight the desired test center, in the "Test Location" drop-down menu. Press the "Register" button. Print your confirmation page and note the date of your upcoming test.
Study for your test, if desired. Read over the SAT book's test guide and practice sample questions, highlighting portions that confuse you. After you complete one pass through the book, review sections that previously confused you.
Visit the appropriate test center on the test date.