how to use this
Cloaking is means of presenting a different web page to a user from the one spidered by search engines. Your server script will have intelligence to differentiate this request. However, it is not an ethical SEO process
Cloaking is a search engine optimization (SEO) technique in which the content presented to the search engine spider is different from that presented to the user’s browser.
It is a black hat technique so i suggest don’t use this for your website, it will harm your site.
For more info please read http://en.wikipedia.org/wiki/Cloaking
Thanks & Regards
As it’s been stated, this is a black hat (i.e. unethical) technique, so further discussion is not warranted.