I would like to know the steps I can take to buy shares, for a common man having a bank account and PAN card.
Its very simple. There are many brokerage firm in India dealing in NSE & BSE. But you should consider the following before choosing a brokerage firm for opening DMAT account.
Reputation of broker : because whenever there is a crash in the market, the brokerage firm account freeze due to margin requirement. Such thing happens with the brokers who provide over leveraged ( margin ) to the customers for over trading.
Brokerage : If you want to be an active trader, the brokerage is an issue you should care for. There are two types of brokerage firm, (i) Traditional like, IIFL, Sharekhan, Trustin and so on ( you can google "open DMAT account online"). (ii) Discounted brokers they are like R.K. Global, Zerodha etc. The discounted broker allow you to trade at fix rates. For example Rs.9 per order or Rs.20 per order irrespective of the amount of your trades. Such types of brokers are very useful for active traders.
CAUTION : First learn how to invest in stock market like fundamental investment or technical analysis trading otherwise it is like driving a car without knowing driving which will certainly cause accident. Your whole amount can be zero without any knowledge. Every new trader or investor does it.
All major private and public sector banks in India have share brokering arm. Most probably the bank you bank with will also have the same. As mentioned in the above post, most banks are full service brokers i.e. they provide you with reports and market sentiments from time-to-time (though their usefulness is a matter of debate). They also charge you higher brokerage on buy/sell leg, with SST it could come as high as 0.8% per leg (though it varies between brokers). On the other hand there are discount brokers, who usually charge a fixed fee e.g. INR 20 per transaction.
However, having said about the brokers, a DMAT account with NSDL/CDSL (depositories) will be opened and the shares you buy and sell will be credited/debited from your depository account. The brokers will provide you with a web platform to conduct your transactions. To open the depository A/C and the trading portal A/C approach your bank or any of the discount brokers. With some of the discount brokers, the entire process can be on-line with signed documents sent to them later. For opening the account you would need ID proof, address proof, PAN card.