The first step is to download all your transactions from CoinCorner and import it into Koinly. There are a few ways you can do that:
Note that if you want to import CSV files, you have to make sure to import your deposits/withdrawals and trades for ALL previous years - not just the current one!
That's it. Don't forget to tag your airdrops/forks so they show up as Income on your final crypto tax forms!