In order to get profit, you must sell at a price higher than the one you bought at. So, when you buy and sell at the same price it is obviously won’t give you any profit. Furthermore, you'll lose money on paying transaction fees. In general, the profit calculation is based on the price growth of the currency and the size of your investment. Let's say, the price is $10,000 and you put $100 – if the price goes up to $10,400, your profit will be $4. There is nothing difficult in it, successful trading just requires more experience.