I have developed a site. I want to change the domain name of this site to be same as our actual website 

For eg.

My site domain name is : mycompany.force.com

and my website domain name is mycompany.com

So now I would like to change mycompany.force.com to mycompany.com

I tried to look into the Site URL rewriter class example, but I dint understand it clearly.

This example shows to rewrite the  path names

Please help and it will be great if you can give me some example codes