Vinit, in your 12th, you should have had Physics, Chemistry, Biology and English as your core subjects. You should  complete your 12th with a minimum aggregate of 50% in your Physics, Chemistry and Biology subjects. It is 50% for General Category, 45% for PWD and 40% for OBC,SC,ST. By doing so, you become eligible for NEET which is the entrance examination for admission to MBBS, BDS, Ayush and Veterinary courses. Now MBBS is a 50 month course. After the succesful completion of course along with 1 year mandatory internship, you need to appear for NEXT and secure a seat in any of the MS Specialisations. Upon competion of the course you become a surgeon. For example, you take up General Surgery, you become a General Surgeon and if you pick up MS in Orthopaedics, you become an Orthopaedic Surgeon.