Simple Sub-domain Question

How do i make a subdoman?

As far a testing goes, this is how i set it up, and i obviously didn't do it right because it is not working. Under co-domains i set up folder.mysite.com and under forward i pointed it to http://www.mysite.com/folder.

What else do i have to do to set up a subdomain?

 

What if i have a dynamic ip address? And use a service like dyndns? How would i do it then?

 

Create a CNAME record for folder.mysite.com that points to your.dyndns.org address.

 

The cname record i would be making in dyndns, or ispconfig?

EDIT - Stupid question. I have to do it in dyndns because they handle my dns.