Update SSL on AWS EC2 Ubuntu

I am trying to update the SSL certificate for a client on AWS using EC2. There are 3 instances and after much mucking about and changing the private keys needed to access them, I was able to finally connect through putty. They are all Ubuntu instances.

• I've tried to follow these instruction but I cannot find where to add this info.
• I've "grep"ed for VisturalHost and nothing comes back except a readme file that doesn't help
• There are no /etc/apache2 directories on any of the instances.
• All three instances have /usr/lib/ssl/certs and /etc/ssl/certs

My questions:

1. What webserver is actually being used?
2. Where can I find the config file to update the location of the SSL certificates?
3. Where would I store the certificate files on the server?
4. How do I know which instance is actually running the website?