Once ether is received the contract will automatically call a fallback function
In this fallback function it will calculate the coins based on msg.value and send the tokens back to the sender address msg.sender
In this way once my contract received ethers it will automatically send back tokens according to a fixed exchange rate
Is this correct?thanks
It's correct way. Have you send external tokens (tokens whitch are existing) from our contract?
If it is true, then see ethereum Crowdsale contract (on official web site) - payable function with transfer function.