Step 1) In your Steemit account go to your wallet and grab your Memo Address under "Permissions" tab.
Step 2) Go to your exchange (bittrex for example) and click the withdraw button under STEEM.
Step 3) You should see Memo and Registered Account. Insert your Memo Address and Registered Account (your handle here)
Step 4) Verify and send! Please test a small amount goes through before sending large amounts!
That is all you have to do!