The first - and in most cases the only - step is to download all your data from electrum and import them to Koinly. There are a few ways you can do this:
Note that if you want to import CSV files, you have to make sure to import your deposits/withdrawals and trades for ALL previous years and not just the current one!
That's all you have to do. Don't forget to tag your airdrops/forks so they show up as Income on your generated cryptocurrency tax forms!