The first - and in most cases the only - step is to download all your transaction data from BBX and upload them into Koinly. There are a couple of ways you can do that:
Note that if you want to use CSV files, you must make sure to import your deposits/withdrawals and trades for ALL years and not just the current one!
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 final cryptocurrency tax documents!