Have you ever tried trading in your entire life? How do you think you are going to buy altcoins anyway? Sometimes you just have to research such topics in this forum and you will definitely find an answer. Anyway, let me give you something to ponder - go to this website https://www.poloniex.com and please do yourself a favor, create an account and then transfer your bitcoins to your poloniex btc wallet. After doing it, you'll surely figure out the answer to the topic.