How do i block unwanted sites with Mikrotik router?

How do i block unwanted sites (using Url or ip address) with Mikrotik router?

This is a example for block Facebook with firewall.

http://www.wirelessinfo.be/index.php/mikrotik/pages/fire-block-facebook

You can block websites with proxy server to

That firewall rule would block not just the web site, but also any other web content that dares mention it in any form.

Proxy will work… For HTTP sites.