Nameservers for what? Your elementfx.com subdomain?
Cause if you bought a domain from somewhere, you set the nameservers with them. If you're trying to set the nameservers on your elementfx.com subdomain, that's not possible as far as I know, as elementfx.com isn't your domain, it'd be x10hosting's, and changing the nameservers for elementfx.com would destroy every other account on it. We just gave you a subdomain on it, but we can't actually change the nameservers on it.
If you bought a domain through x10 though, you can actually go to the clients area and adjust the nameservers there.
