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