Semantic Forms
Ok, i have been checking about it, and SEEMS the way i was trying it, was correct. Anyway, it does not show up instantly (will wait a couple of hours and see).
Actually the way is:
A template can be used to add pages to a category, usually by placing the category link inside tags on the template (e.g. ). When the template is transcluded into the page, the category link becomes active, and the page is added to the category page. This is useful for categories that have high turnover or many pages included, like cleanup categories.
From
http://en.wikipedia.org/wiki/Help:Category
Perhaps someone knows another way to perform an "instant" categorization? This is kind of the indirect way, and seems it needs a lot of time to "oficially" enter the category.