The first and usually only step is to download all your data from GOPAX and upload them to Koinly. There are a few 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 - 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 generated crypto tax reports!