I hope by now you have figured it yourself, but in case you haven't ... open your hive-enging and click on the DEPOSIT button. It will show you a list where you can choose what coin you want to deposit. You choose STEEM and click OK.
Now you will get an adress and a memo. Now you can send your steem with the memo to the adress you got. In no time you will have the (swap steem) in your hive-engine.
Now you can sell your steem for hive.
As soon as sold your steem and have the hive. You can click the WITHDRAW button and withdraw the hive to your hive account by filling in what's needed to get it there.
Very easy and works like a charm.