Make sure mod_proxy is installed on your Apache webserver.
Add the following directives to the Apache configuration file: ProxyPass /webmin/ http://localhost:10000/ ProxyPassReverse /webmin/ http://localhost:10000/ SSLProxyEngine on <Proxy *> allow from all </Proxy>
Add the lines webprefix=/webmin and webprefixnoredir=1 to /etc/webmin/config.
Add the line cookiepath=/webmin to /etc/webmin/miniserv.conf.
In /etc/webmin/config, add the line referer=apachehost, where apachehost is the hostname from the URL used to access Webmin via Apache. If the referer line already has some hosts listed, add apachehost to it.