SAT is conducted globally and is conducted by College Board (US Agency). SAT General is conducted almost 4 times a year and SAT Subject Test is 4-5 times a year. 

For each test you need to register separately and you can choose an examination center from the website, which ever is near to you. 

SAT Registration - To registe for SAT - Students need to create student account on College Board website and then follow the registration process. This will register you for the test, followed by the SAT Fee Payment. 

Admit Card - Once the process is done, you will be able to download your admit card from the account. 

Student Account - Remember this account will be very important for you till the end, all important notifications will be seen here. Just keep it safe ;)