I am using only Binance for now. its good exchange site and the volume is huge also. you can use this site, the exchange site link is https://www.binance.com/ I am not sure as a newbie how you found this one. You can also use Kucoin exchange site. this coin adds new altcoin most of the time.kucoin exchange website link: https://www.kucoin.com/
If you have erc20 coins and not found the coin name on those site than use Forkdelta, here you can also use a smart contract address to do the trade. website link: https://forkdelta.github.io/