To test if private key is installed for the certificate, double click the certificate icon in certmgr.msc. If it has private key, it will show a message in the property page that you have private key, otherwise it will not give any reference the the private key.
To import the certificate with its private key, you can do the following:
- Pack the certificate and its private key into a PKCS #12 file or PFX file using openssl pkcs12. Here's an example.
- Import this PKCS #12 or PFX file into the certificate store.
Note that you may see errors when importing the pfx file, such as 'This file is invalid for use as the following: Personal Information Exchange'. This error was caused by the certificate lacking to appropriate X.509 v3 extensions (such as the usage fields (digital signature, etc))