Hi,
Harvard University is one of the top five Universities of world so its definitely not easy to get there. But nothing is impossible. To get there following are the ways:-

• SAT/ACT-  It is essential to give any of these two tests and attain excellent i must say marks. Many students even get 1600/1600 in it. There is 2% reservation for foreign students so prepare well.
• Open a common application account- It is a portal throughout which you can apply for IS universities.
• The candidates is required to write an apple essay on one of the 7 topics available on their website.
• Two letter of recommendation from your subject teachers
• Your application form- It is most important. It must contain your grades as well as extra curricular activities.
• Only 25% of academics is seen rest is of extra curricular activities. So try to be on top notch on everything. Try to mention all your talents. They will help you. Every year only 6-7 Indians are selected so try to keep your profile as excellent as you can!

All the very best!