You haven't mentioned whether you want to study your Undergraduation or MS in this University. According to the official website https://admission.enrollment.cmu.edu/pages/undergraduate-mechanical-engineering-program, to learn Robotics, you need to join their BS Mechanical Engineering course. For Starters, you need to take up either IELTS or TOEFL based on the requirements of the University. You will need a list of documents and you can check them at: https://admission.enrollment.cmu.edu/pages/undergraduate-admission-requirements . Once you gather all the documents, you need to download the application form from the University and send them across.