Adding/Updating SSL Certificates
From Metro Studios Knowledgebase
You're likely being provided with a zip file that contains two SSL certificates with the extension ".crt". One is a CA (Certificate Authority) certificate and the other is the specific certificate for the hosted site. GoDaddy's CA certificate will be named "gd_bundle.crt" and the site's certificate will be the exact domain in which we want to set up SSL for.
Once logged into Plesk go to the "Server Administration" section (from the left hand navigation) and click on "Certificates".
This will give you a complete listing of all of the certificates currently on the server.
 Adding New Certificates
NOTE: New SSL certificates must be applied to a site that has a dedicated IP address.
Here are a few standards when it comes to SSL certificate creation/CSR generation:
Certificate Name: Should be the exact domain that the certificate is ending up at (even with www if applicable)
Bits: Always 2048
Country, State, City: Should be the location of the client's company
Organization Name: Should be the name of the client's company
Domain Name: Exact domain name, same as "Certificate Name"
E-mail: [email protected]
Next step is to request that the server generates a CSR for your certificate. Click "Request" and it will take you back to the certificate listings page. You can then copy your CSR by clicking on the certificate you just created.
This CSR is what you will be copying over to the CA (Certificate Authority) in order to request a signed certificate. Once you get your site's certificate with the CA certificate you can then use the "Upload certificate files" file upload fields to finish providing all parts of the functional/live SSL certificate.
Once this is complete you can navigate back to the "Server Administration" panel and click on "IP Addresses" to find the dedicated IP address that the new certificate will be applied to. Once you click on the associated IP address you will have an "SSL Certificate" drop down in which you can select your new SSL certificate.
 Updating Certificates
To update a certificate is pretty simple. All you have to do is select the certificate that you need updated and re-upload the CA certificate as well as your site's certificate.
Once this is done it will overwrite the old certificate with the new one.