Finding annual reports is not hard for the most recent documents. The company’s website (often found in the Investor Relations or Information for Investors) will provide the current and often back years of the annual report or SEC documents. You can also find the SEC documents in the SEC Edgar Database.
The Annual Report to Shareholders is the main document public companies use to disclose corporate information to shareholders. Traditionally a separate, polished report, today it is more likely to be a 10-K report with a wrapper on it. The annual report is very similar to a 10-K, including an opening letter from the CEO, financial data, results of continuing operations, market segment information, new product plans, subsidiary activities, and R&D activities on future programs. Keep in mind that annual reports are written by the companies themselves and used as a public relations tool. You might need to read between the lines and consult other resources to obtain a more accurate view of the company.
The SEC documents are required by law and have very specific reporting requirements. Be sure to check for updates to original financials as companies often amend or even restate them in whole.