Upload/Replace SSL Cerfificate on Apache/Ubuntu 12.08 Server

I have a Certificate I need to replace on an Apache Server that just wont allow me to edit the files and replace the content. I have the 3 keys downloaded but not sure how to get it to install. I do not use or know anything about this process. I just need it to work. It is a sub-domain we only use for images but as soon as my main AWS Server's license expired I was able to upload the Certs. This server is beyond my knowledge. A test URL is https://src.bestpricecruises.com/images/hp/gobest.png. You will notice it's cert is out of date. I have all the logins and passwords as well as the same cert I used on AWS. I know it works. Just not sure about the path or if i can simply replace the old SSL or what.