Most universities require that you take the SAT, others allow either the SAT or ACT, and very few don't require either. To have all options open, take at least the SAT once. You can take the test as many times as you want and send the university your highest score. Most students do better the second time they take the test so try and take it multiple times.
You can sign up for the SAT at collegeboard.org. The test does cost money, HOWEVER, if you are apart of JCYC your advisor can give you a fee waiver so the test becomes free for the first two times you take it. Contact your advisor here for more information or to ask for a fee waiver. Not apart of the program? Sign up here!
If you don't graduate high school, you can't go to college! Make sure you check in with them at least once a semester to make sure you are on track to graduate and that you are fulfilling your A - G requirements. What are A - G requirements? Click here!
Your advisors are trained to help you with the entire college process. Not sure what you should be doing? Ask them! Have a specific problem/question? Ask them! When in doubt, always ask your advisor! They are here to support you in any way they can :)