How do I Buy particular scrip?

Press F1 or click on Buy in Action column after selecting the scrip from market watch
You can also Buy from Start Menu > Action >Buy
The Buy Order window will open in docked format at the bottom of the screen

Select the Order Type
Enter the Quantity
Enter the Price
Select the Product Type
Enter the Desired Disclosed Quantity (Not mandatory)
Select Order life (Not mandatory)
Click on Submit Button
Once your order has been placed you will be shown an acknowledgement message with order reference number at the bottom of the order window