Hi Caicai and Baobao,
Welcome!
If you have something in mind, you can bring the design (magazine, etc) to show her, if not she also got lots of magazine at her place for reference too. For my case, I totally have no idea of what I want, so I gave her some request (I would like to reuse the gown for other events later), so she help to suggest some designs. But ultimately, its you who will have to make the final decisions.