I just recently learned how to do this very thing too. Goto your Bittrex wallet, find STEEM and hit the “-“ (minus key)... type in the amount you want to move and your address is simply your Steemit username without the “@“ symbol. It will take a few minutes to show up in your STEEMIT wallet and there is of course a very small transfer fee deducted. I think I moved like 10 STEEM first to make sure things went well then moved the rest separately. Hope this helps!
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