To be able to use your new server certificate, you must make it known to the server service. This is done in the configuration file of the service.
Since the certificate is a server certificate that can be used by several services, it should be stored in a central directory (e.g.: /etc/ssl/certs/).
The private key can be stored in /etc/ssl/private/. Please make sure that only root has read access to the private key.
Certificate chain
In order for the configuration file to be read in again, the service must be restarted after installing the certificates.