How can I get into a college of The Ivy League?

I have been in New York about half years. I am nearly 18 years old now. I am in 10th grade in High school.For Esl and some high school lessons.

I am trying my best to learn. I just want to now, If I want to study in the college which is one of the Ivy League, What should I do and prepare before I graduate from high school in about one-half year.

Please tell me with detailly , and the experienced better.
Such as the preparation for SAT , or THE volunteer and activities .

And other thing important and useful. Thank you.