Before you start searching for information on a company, you need to determine if the company is Public or Private. Typically, there is much more information, including financial information, available on public companies. So, if you are given a list of companies to choose for a research project, my advice is to always choose a public company.
Recent annual reports (10-Ks), quarterly reports (10-Qs), and other securities filings for publicly traded companies are usually posted on a company's web site in an area labeled Investor Relations. For a good example, see Apple's Investor Relations site. If you require access to older reports or financial statement data, you should consult one of the following sources: