The first - and in most cases the only - step is to download all your transactions from BitcoinToYou and import it into Koinly. There are a couple of ways you can do that:
Note that if you want to use CSV files, you need to make sure to import your deposits/withdrawals and trades for ALL years !
That's pretty much it. The only other thing to be vary of is to tag your airdrops/forks so they appear as Income on your generated crypto tax reports!