Let me tell you this first, as a B.Com student, you won't get recruited in the trading roles of investment banking, (if that's what you are imagining). For the sales, trading, mergers and acquisition roles, only MBA students from premier institutes are recruited. 

You can, however, definitely be a part of the back office roles like bookkeeping, clearing and settlement processes, administrative functions, etc. To enhance your chances of getting into such roles, you can do the following courses:

1. FLIP-NCFM Investment banking operations international - https://www.learnwithflip.com/programs/flip-ncfm-investment-banking-operations-international

2. FLIP-NCFM Capital markets fundamentals international - https://www.learnwithflip.com/programs/flip-ncfm-capital-markets-fundamentals-international 

Dear student,
I would like to really appreciate your interest towards becoming an investment banker. As you are doing b.com from school of open learning you have a lot of spare time to do other courses. So therefore i suggest you to join a coaching which offers you a complete study about baking and investment sector. You can do a certified course in that. Also you can go for internships at banks so as to learn more and more.
All the best. I hope this was helpful to you.