Is the part “category” fixed to an URL to an archive or post?

By default, the URL to an article does not include “category”. Only URLs to category archives do, so it sounds like something has already been re-configured.

Anyway, to get the string you want, go to wp-admin->Settings->Permalinks and set the permalink structure to “/news/%postname%/”. That will put the blog posts at “/news/”

If you also want the blog index at “/news/”, create a page named “news” then go to wp-admin->Settings->Reading, click “static page” and set the “posts page” to “news”. You will need to set the static front page to some other page or you will get a blog index there too– same thing in both places.

The same “Permalinks” settings page will let you change the “category” and “tag” strings, which show upin category and tag archive URLs. Look down at the bottom.