Orthopaedics is a specialisation after MBBS. And so you need to study MBBS first. And them you have to study Orthopaedics as a specialisation in your PG. You haven't mentioned  your highest qualification. Let's say you are in your 12th right now, you have to appear for NEET. NEET is the entrance examination for admission to Medical, Dental, Ayush and Veterinary courses across India. Once you secure a seat in NEET, you study MBBS FOR 50 months. Post that you also have to complete 1 year mandatory internship. Post this, you have to appear for an entrance exam for PG courses. Right now it is NEET PG, but it will be soon scrapped off within the next 3 years. Then you have to fulfil the then set criteria and either have to appear for an entrance exam or you will be selected based on your academic marks.