Look up the ticker symbol for the company. Go to you favorite investment research site or ask your broker for the ticker symbol associated with the company. A ticker symbol is usually 1 to 5 letters long. Use this symbol to research your company on investment research sites. If the company does not have a ticker symbol, it is most likely privately owned.
Go to the company's website. Most companies, private or public, maintain a website that includes financial information. The best document to obtain on the website is the Annual Report. It contains detailed financial documents and a discussion of the company's financial decisions.
Use the Securities and Exchange Commission (SEC). They maintain a database called EDGAR (Electronic Data Gathering, Analysis and Retrieval). The database has a listing of all documents submitted to the SEC for public disclosure.
Contact Dun & Bradstreet for privately held companies. They have a website as well as numerous publications that may be available at your local library. Some of their reports may require a fee to access.
Contact your broker and have him connect you to the investment research department. Most brokerage houses will provide you with access to their research team and portfolio.