There are lots of crypto exchanges that you can use on crypto trading including altcoins. But for newbies like you, you should focus first on learning and gathering more knowledge about cryptocurrency and more specially in crypto trading. Because crypto trading really takes a lot of risk, specially those who lack of knowledge about it, because of the high volatility of its market that could be very difficult to anyone to predict of its price.

So, before you start in crypto trading, just make sure that you'd make a lot of research first, to avoid of losing a lot of money and repent in the end.