Hi I have my first therapist appt. next week already pretty nervous  really do not know how to start talking it out

Don't worry, therapist have experience in dealing with first visits and he or she will take the lead and they should work to put you at ease. I would highly recommend writing out issues and concerns or your history with GID so that you can give your therapist as much info as possible with out paying them to drag it out of you.

I find my visits very enjoyable and it can be for you if you let it!

First sessions with ANY therapist, no matter WHAT the cause for scheduling, is as much about building rapport as it is anything else...just remember also that EVERYONE that came through the door of the particular professional was in the same boat as you at one time- EVERYONE had a first session.  The therapist will know how to put you at ease if you are showing signs of being ill-at-ease.