No code needed, Bittrex does support sending STEEM to steamitbeta, which you enter under Registered Acct. Steemit is confusingly simple!

Exchanges have account names like you an me: @bittrex, @poloniex. If you want to send money to an exchange, you'll have to add the code they give you as memo text, so they know whose balance to credit. But the memo text isn't needed for withdrawing from an exchange to your own account.