Annual reports are available for public companies as far back as the early 20th century for companies that have existed for that long, though coverage varies, and there are often gaps with missing years. You may also find 10k reports and other documents, though coverage is spotty, and begins in the 1990s when available.
Search for annual reports by typing the name of the company in the Company Name box. As you type, a dropdown of matching selections will appear. You can click on the company in the dropdown, or click Search. You must enter the name exactly as it appears in the database, so you may have to try variants, spell out abbreviations, and you may have to research name changes over time.
Note: IBM appears as International Business Machines Corp and International Business Machines Corporation. These slight variations lead to different search results.
The SEC filings section of the database appears to offer many types of filings, but in practice, the offerings are very limited, generally only the 10k. These can also be be found as part of the annual report search.