You're not familiar with how wikipedia works? It's the same software.
I've been meaning to add a more detailed explanation and will once I get it squared away and start working on the content. In a nut shell it's for articles that anyone can contribute too. Note the edit button doesn't appear unless you're logged in. Log in first and it might be a little clearer because you'll get all the buttons. Use your forum username and password.
For example maybe you know something about manometers? http://nepacrossroads.com/kb/Manometer
Now if you read over the article and find something that may not be clear, typo, or you want to add something hit the edit button and you can add it.
Once you click save your changes are now public.
Also note there is two distinct sections for each article. There's the "page" and the "discussion". The page contains the article itself. When this button is highlighted to the left you can click the edit button to edit the page.
If you click the "discussion" tab that's for discussing the article. For example if two people have a disagreement over an article or if they wish to make suggestions before changing it they can do it there.
The tabs to the right are relative to whatever main tab is highlighted either "page" or "discussion". If the "page" tab is highlighted and you click edit you'll be editing the article. If the "discussion" tab is highlighted and click edit you'll be editing the "discussion". There's other tabs, for example the "history" tab will give you the history of edits made to an article. This way information can't be loss and you examine what others have changed or edited and reverse changes if you want.