On Coinome’s exchange page, under ‘Sell BTC’ section, you will find 3 boxes called Volume, Price and Amount. This refers to the Volume of BTC you want to sell, the price you are willing to sell at, and the total amount in INR, which is equivalent to Volume * Price. You need to enter any 2 of the 3 boxes, and then click on Sell.
If the sell price matches an existing buy order, the order is executed instantly. Otherwise the order remains in the open order book, till a buyer comes and matches it.