The anxiety you feel is not unusual. The vast majority of us have felt that at one point or another. It is important to note that it isn’t permanent!
So, happy that you are here and I hope it will be a good experience for you.
I encourage you to complete your Profile page. It goes a long ways towards helping other members to understand you and your journey. It can also be updated at any time if things change. This is in contrast to regular posts which are locked shortly after they are submitted.