You can install a self-signed SSL if you have a VPS account with PremiumRDP. Just log into your WHM (Web Host Manager) -> SSL/TLS
and click the Install an SSL Certificate on a domain button.
Hit the Browser Certificates button if you have a self-signed SSL created already. Here is how to create a self-signed SSL.
If you have a Private SSL certificate, you need to ask your SSL provider for the SSL details and enter them in the fields accordingly.
