How to set-up a subdomain

I've used cpanel to setup subdomains for websites I've worked on. It hides all the work so when I had to create a subdomain for a virtual privates server where cpanel is not installed I had to figure out how to make it happen. I won't explain all of it right now, but I'll tell you a first step.

STEP 1: Add the subdomain as a cname to your resource list.

See this page for an explaination of cname (canonical name).