@bobaphet i am honored to make this post for you yes you need to create account at coinbase here is the referral link https://www.coinbase.com/join/5a27132e75ec4b011c4d1b17 when u sign up for this u can transfer your steem to coinbase and from coinbase to your bank account . If you want to invest in other coins binance is the most secure exchange here is the link https://www.binance.com/?ref=16026369
Now you still need to buy bitcoin or ethereum on coinbase before you transfer to binance to buy other coins i know this is alot of stuff i also left you links on this post for you to learn thru.