HiI would like "registered" users to comment global as well as add articles to the "ARTICLE" section.The other guide is written in appaling english with no step by step guides.I've tried making use of the USER GROUPS, but when I create a user group "SUBMIT ARTICLE" and add a user to it, then he cant comment on anything else besides items in "ARTICLES". And that is not what I want.

It appears that a user can only be a member of one group.
and
Groups do not have sub groups that inherit permissions.
The only way i can think of quickly is to make registared able to comment on everything and
Create a group for the category Articles, with ability to add items and
let them use a different user - you might run into email address problems...