You may find that after importing an SSL certificate, it doesn’t appear in IIS. To make the certificate appear in IIS, you must import the certificate as a machine certificate.
Double clicking on the certificate may not let you import it as a machine certificate. To fix this, run MMC from the start screen and add the certificates snap-in, specifying computer account to manage. Then navigate to Certificates -> Personal -> Certificates. Right click and import the certificate (you may need to change the certificate type in the open dialog box before your certificate appears to be able to import it).
After this, the certificate should appear in IIS under Bindings when you select HTTPS. If it still doesn’t appear, ensure that you also have the private key.