The first - and in most cases the only - step is to download all your transactions from BTCC and import them to Koinly. There are a couple of 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 years !
That's pretty much it. The only other thing to keep in mind is to tag your airdrops/forks so they appear as Income on your final cryptocurrency tax forms!