From LipidomicsWiki

How to put an article in a category

Putting an article in an existing category is quite an important and easy issue.

Just do following in your article (by convention, at the end of the page).

[[Category:''Category name'']]

Substitute the actual name of the category in place of Category name. To be specific, in order to add an article called "Albert Einstein" to the category "People", you would edit the article and add "[[Category:People]]" (no quotes) into its page source somewhere.