Sharing what you know, as long as the information you posses is valuable, makes everyone better. You should not be afraid to share as sharing only might pass the surface knowledge you posses. Sharing passes parts of your experience or understanding of things, but the most powerful tool you posses will still be your experience and skill, usually accumulated in many years of working in a specific area.
If the only thing towards your new business is an idea that you think that keeping it hidden might get you a certain advantage you are certainly wrong. The first mover advantage still stands, but in the end only the best implementation of that idea will win in the current market situation. Everyone has ideas but fewer people are capable of creating a great business out of them.
So get out and talk to people. Tell them your plans and ideas and see if you can find a business partner to help you creating the next big thing you have in your mind for some time. Ideas will never be as valuable without the right people implementing them so try using your idea and knowledge to form the best team possible and get to work!