Display one special post

WP does that out of the box: by clicking a permalink (e.g. the title of a post) only one post is displayed.

Look at this article:
Template_Tags/query_posts

also at the bottom of that look at the Resources section for some good links to examples.

Hm, yes, I will see, what query_post can. The reason for my question is: I want to build up a cms with wp and on the first page I want to display exactly defined content (eg post 3 in category “portfolio”).

You can try this plugin:
https://guff.szub.net/2005/01/27/get-a-post/

Ah, yes! Thank you both.