i recommend coinbase but they get pretty high in fees, binance is what i use but you can deposit cash have to transfer like bitcoin to thier exchange and trade for other coins, but theres robinhood trading app which has a few crypto currencys you can trade ands it free just no way of exchangeing them to a hard wallet .... www.shotcallertrades.com is my referral site you can click on the logo and get a free stock, or cash for using one of my referral links . good luck in your crypto trading