To place a buy order with NRML:
On home screen. search the stock you wish to buy
Once you have clicked on the stock you want to buy, it will take you to the stock details page. On the top right corner select the exchange (NSE/BSE).
At the bottom of the screen click on buy button
Enter the number of shares you wish to buy
Enter the buying price to place a Limit order or choose the product type as Market to place a Market order.
Select the product type as NRML
Swipe to Buy and place the order, on the order confirmation screen, click on view orders button to view your order in the order book.