Ok this is how it is done.
Go to your Coinexchage site, Balances, and find at the bottom kB3, click Actions, Click Deposit, new page opens in which you can generate new deposit address for kB3 coins. Save it.
Then go back to balances and click your B3 Action button, select Withdraw, then follow the instructions and paste your kB3 address where you want to send your B3 coins. Done deal.
I just tried to do this, but the B3 was in maintenance mode.. so I must try later again.