To install this once you have got to the installation screen you will need to fill in all the correct information in the relevant areas.
Step 1 : In the first box, you will need to paste your domain / site certificate from the zip file that you received from Positive SSL.
Step 2 : Fill in the required domain / user / IP address information.
Step 3 : In the middle box, you will need paste the correct RSA private key that was generated with the CSR that you sent to Comodo to get your certificate generated.
Step 4 : In the bottom box, you will need to paste the correct PositiveSSLBundle file for you certificate.(which you can download from our support section also sent to you in the zip file as XXXXXX-ca-bundle)
(this is the combined AddTrustUTNServerCA and PositiveSSLCA files supplied in the zip file that was sent to you and is also available from the support section of the website.)
Step 5 : Press the "Do it" button