Here are the markets STEEM is traded on.
https://coinmarketcap.com/currencies/steem/markets/

I use Probit in the US at this point. It didn't require a bunch of complicated registration. Just e-mail address and then you should be able to get some DOGE or something else and send it to a wallet on your computer. I have been using the Atomic Wallet as well as the Exodus Wallet and also have coins on the Ledger Nano hardware wallet. I hope Probit helps