How to setup Subdomain for S3 Bucket

Hi everyone,

I have an existing website that resides on a non-aws cpanel server. My domain is registered with godaddy. I created an S3 bucket and would like it to be a subdomain of my main site (ie library.mainsite.com). I've looked through the documentation and help docs. Unfortunately most of the writers assume prior experience and thus omit important steps. Can someone please point me to good beginner documentation for this. I'm getting conflicting information even within the AWS community. Some people are saying create a cname entry. Other people are saying it's nameservers. I'm very confused.

Thanks