Dear Shivraj, IIM Pune offers PG Diploma courses. You cannot pursue a PG Diploma after your 12th. You need to hold a Bachelor's degree to pursue Post Graduation or Post Graduation courses. So after your 12th, you should pursue Graduation in any discipline and secure atleast a minimum aggregate of 50%. It is 50% for General Category and 45% for Reserved Categories. Next you have to appear for CAT. CAT is an entrance examination for admission to IIMs and top B schools of India. Once you appear for CAT, based on your percentile and academic profile, you get shortlisted to IIMs. Then you have to attend Group discussion and Personal Interview rounds. The final score will be calculated and you can seek admission. This is the same procedure for all the IIMs including Pune and Rohtak.