To enable use of a shared SSL certificate, you will want to login to your CDN.net control panel at https://hb.cdn.net/
From there, navigate to the CDN resource you will be adding the shared SSL certificate to. Click on the security tab.
Once on the security page, click the check box that says, "Enable SSL." Then click "Shared SSL." A box will drop down allowing you to appropriately name your shared SSL address.
Once you have enabled the shared SSL certificate, you will want to link to your CDN hosted assets using the new URL. In our example, the URL we would link to would be https://lux.r.worldssl.net.