Encouraging knowledge sharing and social learning is an important priority for many companies but one that isn't easy to accomplish. Some options lack privacy; others are unfamiliar to employees or difficult to use. However, if you have some coding know-how, you might find that MediaWiki supports your needs.
It lets you create wikis, which are websites that enable users to collaboratively create and modify content. Think Wikipedia (which is, in fact, powered by MediaWiki).
As an open-source server software, MediaWiki is free for your company to download. You can install it on a company server and then set up a wiki on your organization's internal network—where only insiders can view and edit it. Employees might use it to explain what their teams and departments do, document standard procedures, or point people to specific forms or resources. For example, your marketing department might build one page that describes the role of everyone on the team, one that explains how to monitor traffic on the company website, and another that links to forms for putting in advertising requests.
If that tool sounds appealing, you may want to have someone on hand during the setup phase who can code in PHP—the language in which MediaWiki is programmed. After that, though, the software has its own built-in editing tool that you don't need any type of coding knowledge—not even HTML—to use.