Where can I find information on corporations, LLC's and non-profits?

The best source of information is the NYS Dept. of State website at www.dos.state.ny.us. You can search for corporate names, obtain corporate forms, search for by-law information, etc.The most common question is "How do I register a d/b/a for my corporation?" If a corporation wants to do business under another assumed name, they must file a d/b/a. There are forms available on the website to accomplish this.