The first - and in most cases the only - step is to download all your data from HitBTC and import them to Koinly. There are a couple of ways you can do that:
Note that if you decide to import CSV files, you need to make sure to import your deposits/withdrawals and trades for ALL previous years and not just the current one!
That's it. Don't forget to tag your airdrops/forks so they appear as Income on your final cryptocurrency tax reports!