Well for one thing, you'll need to register your co.cc domain at co.cc and then set the nameservers to ns1.x10hosting.com and ns2.x10hosting.com
After that, clear your browser's cache when checking up on your site. The nameservers might resolve immediately or they might take up to 72 hours to resolve.
co.cc is not part of the free hosting. x10hosting doesn't control nor own co.cc. It's a third-party domain service that you must register at their site. The domains that you register there are mostly free.
The link to cPanel is not at the top menu. I said to click on Hosting at the top and it'll take you to your hosting details. On that page that shows the hosting account details you should find that button to login to cPanel.
Did you follow my last instructions? Please verify that and reply in detail what it's doing when you try to login such as specific errors and the like. Your site is showing up just fine. Please clear your cache.