Imposter syndrome happens to everyone, so believe in yourself, and if you need to doubt something, doubt your self-doubt.
This seems obvious, but you get what you give, so get out of your comfort zone.
The dev communinity is very helpful, and there are many resources to find answers to anything that is stumping you.
Listen to podcasts, read articles, talk to like-minded people. Even if you have no idea what anything means, you will, eventually.