Which course should I pursue in the IT field after completing B.Com?

Hello Bikram, It's nice to know that you want to learn more. Perhaps, you should learn Java, or analytics. I am giving a link to a govt website that will tell you about different courses available in market: http://beta.nielit.gov.in/content/short-term-courses-software

If you know basics of programming then you can go for different courses in IT like C , C+ , JAVA, .NET, etc. programming languages. Other many opportunities are available or join a course you are interested in. It may start your career in IT sector.