Binance
Kucoin
Bittrex
Bitmex
Exscudo
Poloniex
Hotbit
That's the list that you can buy and sell a cryptocurrency. And don't panic buy and sell because you may lose your funds.
I prefer to choose binance, especially if I am a new person who wants to try trading. Binance, as a big exchange right now, is giving a chance for every trader or new people to trade by selecting many coins so they can make a profit. But before you can try to trade, you should prepare yourself by learning some lessons about trading so you don't get confused with trading and you can also make a profit. No matter in what exchange you trade, as long as you know the basics of trading, you will have a chance to make a profit.
So that is the important thing before you want to trade in any exchanges.