The first and usually the only step is to download all your transactions from CoinField and import them to Koinly. There are a couple of ways you can do that:
If you decide to use CSV files, you have to make sure to import your deposits/withdrawals and trades for ALL previous years !
That's all you have to do. Don't forget to tag your airdrops/forks so they show up as Income on your generated cryptocurrency tax documents!