1. Choose the currency
Let's assume you have Bitcoin and you want to have Ether. Here is how the exchange occurs.
Choose BTC from the drop-down list in the first field and enter the amount of Bitcoin you would like to exchange. Then choose ETH from the drop-down list in the second field. The approximate amount of Ethereum you get will be calculated.
2. Enter the recipient's address
Enter the Recipient's Address. Ethereum will be sent to this address. Be careful and make sure you use the correct Ethereum address.
Check all the information you have entered. If everything is correct click the Exchange button.
3. Send and receive coins
You will see the Payin Address (the address you need to send your Bitcoin in order to finalize the transaction). Send the required amount of Bitcoin to this address.
That's it! In a few moments, your Ether will be sent to you.