Id' say just approach it with an open mind. It's just the first session anyway so there won't be nearly enough time to delve into all the subjects you bring up even in just this one message. They will probably start with some very basic questions and allow you to answer as you feel comfortable with. As you build trust and familiarity you can open up more as time goes on. And remember, the only motive the counselor has is to help you get better.