I have download Mahasecure app, but don't know further procedure for applying Internet Banking.
You have to contact your bank because only the bank representatives have the possibility of enabling and disabling options for your account. "Internet Banking" is an option that can be enabled or disabled for customers. It's not enough to only have a bank account, because the option has to be activated manually.
You can use the following link to get in touch with them: https://www.mahaconnect.in/jsp/ContactUs.html