The proper steps would be:
1. set the nameservers to ns1.x10hosting.com and ns2.x10hosting.com
2. Add the domain as parked or addon domain depending on where your wordpress is installed, if on main domain you would want the parked option.
3. login to the admin area of wordpress and update the settings (settings->general; update "site address" and "wordpress address" options) to reflect the new domain you want to use, if you do not do this last step you will see a redirect to the domain wordpress was initially installed under.
If that doesn't work, please describe more in detail what happens and what you would expect so we can help troubleshoot better.