Welcome aboard to our bipolar forum.
I agree with everything serafena explained. She has practically covered everything and very well too.
The only other suggestion that I have for you is to bring notes.
Jot down things that you go through. The types of moods you have, how high and how low they go, if you have anythings that trigger a certain mood. What changes if any that your family members or friends see in you. Things that are difficult for you or hard to deal with. Or lists of things that really excite you.
I would also like to stress the importance of being totally honest. If you're not...you're not helping yourself, only hurting yourself and wasting your time.
Good luck. Keep us posted.