Congratulations on starting your college-bound experience. It's not too early to start thinking about your goals and setting your priorities and expectations. Universities will look at everything you do beginning in Grade 9 on to determine your admissability. I commend you for being proactive!
As you know, UCLA has a competitive admissions process. I would recommend looking at the UCLA Undergraduate Admissions website (http://www.admission.ucla.edu/infoprospective.htm) to become familiar with the requirements and materials needed for applying. In addition, if you have the ability to visit campus - GO! Regardless, reach out to the admissions counselor at UCLA who recruits at your high school (http://www.admission.ucla.edu/meet-your-counselor.htm). If an appointment isn't possible, email and ask thoughtful questions about what they look for in a potential new student. They can give you some direction and offer insight.
You may also learn about opportunities for high school students to engage on campus during breaks or the summer. http://www.ucla.edu/search?qa=programs%20for%20high%20school%20students
Opportunities abound! Take advantage of the resources around you and enjoy! Wishing you all the best -