My children spend too much of their time on Facebook or other sites like that. Is there any way to block them all?
You can block site with Aobo filter. It is quite easy to use.
There are a couple of ways to block those website and the most common are:
Use a parental guide application. Developers released many apps that have the capability of blocking the files, and you can find some of them through the link: http://software.informer.com/search/parental+software
Accessing your router to manually add the websites to the blocking list. This is also effective. You can even assign custom browsing hours to block them or not.
Using an Internet Security Suite that has the capability of adding custom websites to the filtering module.