You can buy/sell cryptocurrencies by using a cryptocurrency wallet and an exchange. You can choose a cryptocurrency wallet that supports the coin you wish to buy/sell. Once you have chosen a wallet, you can then sign up for an account on a cryptocurrency exchange such as Coinbase or Binance, where you can buy and sell your chosen cryptocurrency. It’s important to make sure that you do your own research and compare different exchanges before deciding which one to use. Additionally, you should also take into consideration the fees associated with each exchange, as they may vary.