There are a lot of resources that contain information about companies. Try to determine whether your company is public, private, or subsidiary. Don't limit yourself to library resources - look at social media like Twitter or YouTube, patents, corporate filings, investment activity. And don't forget to do an article search in trade and industry publications.
Keep in mind that not all company information is openly available - companies do not want their competitors to know how they do what they do, or how much of it they did last year or ten years ago, or whether they do it well or not. However, with ome digging and creative thinking you can often get to deeper levels of company information!
Search on a company name, an executive's name, etc. Local publications are often the only place to find info on private companies.