Instructions:

1. Open the Internet Services Manager or the Microsoft Management Console (MMC) containing the Internet Information Services snap-in.
2. Expand Internet Information Services (if needed) and browse to the Website you plan to secure.
3. Right-click the Site and then click Properties.
4. Directory Security tab.
5. Secure Communications, click Server Certificate.
6. On the Web Site Certificate Wizard, click Next.
7. Choose Process the Pending Request and Install the Certificate, then click Next. 
   Important: The pending request must match the response file. If you deleted the pending request in error you must generate a new CSR and replace this certificate.
8. Select the location of the certificate response file, and then click Next.
9. Read the summary screen to be sure that you are processing the correct certificate and then click Next.  You see a confirmation screen.
10. After you read this information, click Next. Stop and start your Web server prior to any testing.

Be sure to assign your site an SSL port (443 by default).
 
If you do not specify an IP address when installing your SSL Certificate, the same ID will be used for all virtual servers created on the system. If you are hosting multiple sites on a single server, you can specify that the ID only be used for a particular server IP address.