Help:Category
Main categories
Each article should belong to one of these categories. Just type [[category:CATEGORY NAME]] at the bottom of the article.
OS categories
If the article only applies to a single OS (or OSes) you should add OS categories to it. The OS categories are Linux, Mac and Windows.
Language categories
One advantage of the wiki is that articles can easily be translated or written in a language other than English. If you do this write the article title in its native language followed by the language in brackets. Then add it to a language category such as Deutsch, Italiano etc. If yours is the first article in the language go to the category and add the category to Languages.