Hello...
For taking admission in IIMs you have to appear in entrance exam and qualify with good percentile.Exams like CAT,MAT,XAT etc is conducted every year for providing admission  in it.You should make preparation for this .There are very good management colleges through CAT exams.For eligible in appearing in CAT exam you should have 50 percent or equivalent CGPA marks in bachelor's degree.
Hope it helps you.
Good luck.

Hello Shubham,
For take admission in IIMs, you have to appear in CAT exam.
Basic Eligibility Criteria. According to the IIM admission criteria 2019-21, candidates appearing for CAT 2018 must have a Bachelor's Degree with at least 50 per cent marks (for General category) and 45 Percent (for SC, ST and PWD category) or equivalent CGPA from any recognised university.
All the IIMs usually follow a two-step selection process. First, short-listing on the basis of CAT score and then WAT and PI rounds for the short-listed students.
More information, visit to the given link
https://www.google.com/amp/s/bschool.careers360.com/articles/iim-admission-criteria/amp
Thank You.