The marvellous thing about Wiki is that not only can you see all the things that this page links to, you can see all the pages that link to this page using the BackLinks field in the right hand sidebar.
A category is created by adding the category title, in this case CategoryBeginners, to the bottom of the page. It says "I think this page is relevant to this particular category". Then, by putting some special wiki magic into the page, a category listing is made. (If you want to know how, edit this page).
To reiterate: to add something to this page, don't edit this page; go to the page you want to link and add the phrase "CategoryBeginners" (normally under a line at the bottom.)
A collection of notes for beginners to look at to learn more:
GreatHomePageRefactor?
Part of CategoryCategory
18 pages link to CategoryBeginners:
