Doubt is a persons downfall. It causes us to undermine our skills and undermining ourselves causes our confidence to deteriorate expoentially. When our confidence deteriorates, our skill in whatever we had confidence in is now also deteriorating. Although some people are born with skill, it is somehting you have to work towards. Just because you know nothing about something right now, there is no reason that you can't try to learn about it. Even professionsals were once like you, they had no idea what something was so they trained and learned in order to be the heads of their fields. Nothing should stop you from at least trying to learn what you want to do as a career, but you have to know that sometimes it just won't work out and that you may have to learn something else and try to improve yourself and your knowledge in said subject.
That being said, even the greats had doubts in their skill, so they learned from their mistakes, adapted to them, and they are better now for having learned those mistakes.