How to set up a 404 page?

I try to set up a 404 page but something goes wrong.

I don’t have a ht access file on the server but there is a map “errors_docs”. One of the docs in this folder is called “not_found.html”. When I edit this file nothing happens. I created a rule ErrorDocument 404 /errors/404/index.html

“errors/404” is the folder and the document is named “index.html”.

Any suggestions ?

I think it depends a little bit on the server configuration but in my case it worked by creating a page for "404.shtml"and I gather the shtml extension is particular for 404 pages. I also added a timed redirect to the header meta tags but that is a personal choice.