The first and usually the only step is to download all your data from altcoin trader and import it to Koinly. There are a few ways you can do that:
If you want 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. The only other thing to be vary of is to tag your airdrops/forks so they appear as Income on your final cryptocurrency tax reports!