[Updated 10.2023]
The fastest way is to use WhiteBIT's CONVERT function.
To buy EDC, please refer to this FAQ article:
https://edcoin.freshdesk.com/a/solutions/articles/82000905402
To sell EDC, please refer to this FAQ article:
https://edcoin.freshdesk.com/a/solutions/articles/82000905403
Within the CONVERT function, you can specify other digital assets/crypto that you want to buy/sell.
You can learn more about how to trade on WhiteBIT as a newbie by referring to this WhiteBIT blog article:
https://blog.whitebit.com/en/trading-for-newbies/