Phpnow1.5.6 how to set the 404 exception page

Phpnow1.5.6 how to set the 404 error page? In phpnow1.5.6, how do I set the 404 error page? Directly in http. in the conf file, when there is only one site on the server, it will be okay. when two sites are configured, it will not work. I still don't understand what experts know, each virtual host is set or each virtual host directory contains 404 phpnow1.5.6. how do I set the 404 error page?
In phpnow1.5.6, how do I set the 404 error page? Add it directly in http. conf. when there is only one site on the server, it will work.
When two sites are configured, they won't work. why don't you know if you have any experts?

------ Solution --------------------
Each virtual host has
Or each virtual host directory contains 404 processed files.
------ Solution --------------------
Create a. htaccess file in the virtual root directory of the site and write the following code:
RewriteEngine on

ErrorDocument 404/404 .htm

Just drop 404.htm to the root directory.