You will need to research and possibly create your own opportunities at the school level, your town, and also state, national and international options. For example, your school may or may not have a literary magazine or a Spanish culture club or an international club open to watching movies in other languages. Likewise, places you can get to locally may have teen reading and writing clubs (check local public library announcements). If you don’t find a group you want to join, then create your own. My daughter started a Computer Science Club at her school in 11th Grade – this was at the beginning of the year so easier, but you could set up the foundations of a new club at your school to start next fall, with you as President.
Online, there are many options for publishing or writing – e.g., NaNoWriMo every fall, and essay contests, poetry contests, blogging, etc. You can browse some contests here: https://cogito.cty.jhu.edu/competitions/ or go to Google.com and research “high school English competitions.” There are also national Spanish language tests/competitions.
You will want to take the SAT subject tests in English and possibly Spanish, in addition to preparing well for the reading and writing portion of the SAT and ACT.
Look around for summer possibilities like teaching at a summer camp that uses some of your interests and skills, where you are paid to help others, and also for volunteer activities right now. Perhaps you can volunteer to help Spanish-speakers with English, or vice versa. Is there a Latin American Association near you that you could get involved in?
Make a list of all the books/stories/poems you’ve read for fun in high school outside of requirements for school, and then consider creating a list of books or short story anthologies to tackle over the summer, with some possibly related to your heritage and in Spanish. The list might become the basis for your Personal Statement or another essay when you apply to college. For books and stories in English, make a note of any word you don’t know while you’re reading and create your own dictionary of these words, to help you with the SAT later. (You could do the same for Spanish to help you with the SAT Spanish test.)
Keep an eye on what UCI is looking for here:
http://www.admissions.uci.edu/applicants/freshman_admission.html
http://www.admissions.uci.edu/applicants/freshman_selection.html
Research suitable majors here:
http://www.admissions.uci.edu/about/academics/humanities.html
You could possibly major in English and minor in Film and Media studies, or possibly minor in Spanish to be able to read Spanish literature with others.
Also research similar majors at a variety of California universities in case you do not get into UCI, so you know the other places you would be most interested in attending.