How do I convert Steem to BTC? The market place here is a little confusing...

I'm trying to convert Steem to BTC... when I go in the market place it seems like I can only sell Steem for Steem Dollars?

I want to convert it to BTC... should I just do it in Bittrex?

In Bittrex, when I try to deposit Steem here's what I see:

What does it mean by

To deposit coins, use the Memo and Registered Account in the transfer command:
transfer "<from_account>" "bittrex" " STEEM" "<memo_message>" true

What.... ? Don't I just use the address that is displayed in the Memo field?

Sorry, just want to make sure before I lose a lot of money.

Thanks!