Welcome to PC

From what I know, CBT is exploring things you can think (cognitive) and things you can do more practically (behaviour) to manage your symptoms. So identifying negative thought patterns that may lead to certain behaviours and feelings and trying to challenge them by replacing with positive thoughts. So for example there may be negative thoughts that reinforce your agrophobia, "what ifs", catastrophizing - "something awful may happen" and replacing with more positive reassuring thoughts. Then looking at practical things, such as just going out for a small amount of time, then extending while using the thoughts you have practised.

Biofeedback I don't know so much about, sorry.

Do you have a therapist to help you learn these things?

Soup