How do I force people to like my facebook page before accessing the accompanying website?

[Jonis]

I have a search site which I share, but I would like some more advertising for it.
So if someone likes a page on facebook, hes friends will see he likes that, they'll check out the page and maybe also like it.
But why would people like a page if it is just optional?
I've seen websites where you have to like a facebook page before having access to the website.
If you didn't like yet you see another screen which gives of course a like button.

Example: http://readysettroll.com/images.php?i=5UfhT

I also have a web page, a facebook page (app).
Can anyone make or give me a html code to do a thing like that?

Thanks

[CofeeNate]

I'm not exactly sure what you are trying to do, but you can't require people to 'like' your facebook page in order to visit your website. However, you can show one view of your facebook page to non-likers, and another to those who 'like' your page. This is only able to occur inside of an app, though. You will have to run ads or other promotions to the url of that app, instead of to the general page link. In order to get this functionality, you will want to install the HTML iframe app to your page. Just search for 'HTML' inside of facebook, then click 'apps' on the left side. The icon is a star. Install the app on your page, and it is pretty straight forward. This is called 'fangating'.