Two things here, firstly how is this related to HR questions and issues?
Secondly, if you know nothing about Hindu matrimony, then how are you going to start a business and be able to talk to clients? You are setting yourself up for failure. Have you written a business plan about how the business is going to operate, how you will market it, and what your financial plan is to establish the business. You will need to have a large sum of money put by to cover the set up of the business, and expenses for at least the first 12 months. You will also need to have 12 months living expenses put by to cover you until the business can support you. No business makes money from Day 1.
Start by finding employment with an established agency and learn about the business. Then later on you can think about starting one yourself.