Zero
OK.....
With a registrar, you list your nameservers. In your case, it is F2s.
This is the nameserver that is responsible for publishing the records
for your domain to the rest of the world. For anything to resolve they
have to have records for your domain in their nameserver. There are various record types, A, Cnames, MX, and others. an "A" record points a domain name to an IP address. A Cname points a domain name, to another domain name. MX is used to point mail for a domain to the proper address.
When browsing by domain name, you start several things. On your local
machine a query is sent to a dns server. The dns server looks up who your
name servers are, and forwards a request for the record you asked for to
the server who is Authoritative then replies with the IP address that was requested. It eventually gets back to you.
So just having nameservers listed, doesnt do anything. If F2s does not have an address for
www.domain.com on their server, nothing happens.
There are a number of commercial dns hosting services that will do this for you, but most will charge for hosting, or for each change for a
domain.
If F2s allows you to change the A-record associated with your
www.domain.com record then you could just go there to point that
to where you wanted.