Using a Comodo SSL cert with AWS

Hello,

I just downloaded the zip file with the 5 *.crt files in it and would like to set up an HTTPS proxy on Amazon Web Services. Their form is asking for a Private Key and a Public Key Certificate. How do I get those from those 5 .crt files ? Sorry if it was asked before, but searching did not yield anything to me.

Thanks,

Balazs