You need to prepare for and crack the Civil Services Examination conducted by Union Public Service Commission (UPSC). You have to pass through Prelims, Mains and then Personality Test (Interview). As per the eligibility criteria, you must be completing your graduation from a recognized university. And your age should be between 21-32 years of age providing you're from general category. For more details, refer to the site below..

https://competition.careers360.com/articles/upsc-ias-eligibility-criteria/amp

Also a preparatory tip for cracking the exam is attached over here. Refer to it too..

https://competition.careers360.com/articles/how-prepare-for-upsc-ias

Best wishes. Thank you.