CaiGengYang, no one can get to the page you created because the web address (URL) you provided is apparently on your local machine. You need to provide us a web accessible URL. Good luck.
file:///Users/CaiGengYang/Documents/CaiGengYang.html is a local file on my local laptop because it has the "file://" scheme and thus is inaccessible to other people besides myself.
So how do I create a personal site like this : http://www.paulgraham.com/ which is fully accessible to the public ?
Github is a remote host for Git repositories - if you don't know how to use git then you're going to need to learn. If you do, great. Since your profile says you're trying to become a programmer and want to work for Google, it's a necessary skill.)
There are other ways to host a site as well, typically involving an account with some service (Godaddy and Hostgator are two popular ones but there are hundreds of options) and registering a domain name, and uploading the files (usually by FTP though modern services deploy by git as well) to the remote server. Then the domain name points to the files on that server.