Your customers want information. You have it. So give it to them.
Communication is the key and the beauty of the web.
Whether it be a sexy marketing campaign or a simple instruction manual, the important thing is the dissemination of ideas. If there is no vlaue in it for your visitors, they won't stay and definately won't return. If you tell them you have it, but they can't find it on your site, they are going across the street to get it. And they probably won't come back. You only have one chance to make a bad impression.