The first and usually the only step is to download all your transactions from Cryptonex and upload them to Koinly. There are a few ways you can do that:
Note that if you decide to use 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 pretty much it. The only other thing to keep in mind is to tag your airdrops/forks so they show up as Income on your generated cryptocurrency tax forms!