QUESTION Newbie asking for tags and categories, posts

[Felix]

Maybe it was not the best idea but i tried it on a production new site.
Now, the site is broken. How can I revert back to the former situation ?
Edit : I removed the folders of the plug in and the php file and it was back ok.

Did you really risk your production site ? You didn't make a backup first ?
That is not the way how to work with production sites.
Install a fresh new GS setup and then try the News/Blog plugin.