A company's website is the online mouthpiece of that corporation. Some companies have multiple websites: a consumer site for people to purchase goods or services and a corporate site for investor relations and information about the company. Companies usually have links to more information about the corporate structure under an About Us section.
If you cannot find the company information you seek, make sure you have the name of the corporate entity correct and are not using the product's name.
If you know that you need to search a specific site or domain, you can use Google to search for you. Advanced Google Searching gives you the option to search only one website or a domain (.gov, .com, .edu etc.). If you can't find the information that you need by searching a corporation's site, you can use Google to search the site for you, the results you get will be only from that website.