Open the ZIP folder containing your certificate. Save the file called your_domain_name.cer on the desktop of your server. On the Start screen, click or search the Internet Information Service management (IIS) and open it. Click on the name of the server. In the main menu, double-click on the Server Certificates button in the IIS section (located in the center of the menu).

From the Actions menu (on the right), click on Complete Certificate Request... It will open the Complete Certificate Request Guide.

Navigate to the _domain_name.cer file that COMODO provided you. Next, you must enter a friendly name.

This name is not part of the certificate itself, but it is used by the server administrator to easily identify the certificate. Select the new certificate in the personal certificate shop.

By clicking on OK, the server certificate will be installed.

Note: There is a well-known IIS 8 request, which presents the following error: "Failed to delete certificate". If this is the same server where you created the CSR, in most cases, the certificate will be installed. Simply close the dialog box and press F5 in order to renew the server certificate list. If the new certificate is now on the list then it is installed on the server, but you should check and make sure that the certificate is in the Web Hosting section. If not, you can move it there, if it isn’t included in the list, you will have to repeat your certificate’s version using the new CSR (see instructions to create a CSR for IIS 8). Since you created a new CSR address, log into your COMODO account and click on the button to replace your certificate.

Once the SSL Certificate has been installed successfully on the server, you will have to register that certificate on the appropriate website using the IIS service. From the Connection menu in the main service administrator window Internet Information (IIS),select the name of the server where the certificate was installed.

In the section Sites, select the website that you want the SSL for. From the Actions menu (on the right), click on Bindings ... This will open the Binding Sites window.

In the window Site Bindings, click on the Add… option. This will open the window Add site bindings.

In the section Type, select https. The IP address must be the one belonging to the website or All Unassigned and the port above which the traffic is secured with the SSL is usually 443.

Click on ΟΚ.