Hi Raja,
Open the new DEMAT account. When you had opened the old trading account in Oriental Bank of Commerce, you will have received a "Delivery Instruction Slip" booklet. It is like a cheque book for DEMAT account. You have to fill these slips appropriately and give to your new DP. You new DP/broker will help you with the details.
The transfer is charged on a per scrip basis. I think it was around Rs. 20 per scrip. Get it confirmed from your broker.