I can't understand this post. First of all, if you block an IP address you only block *one* site, not the entire Internet (unless you're talking about blocking the IP address of the computer in question). Secondly, the grammar in that post is hard to understand.
However, to block Internet access from a particular user, what you would do is take the Internet configuration files (/etc/hosts and /etc/resolv.conf) and edit the permissions on them so that the user(s) in question cannot access them at all -- perhaps by logging into that user's account and typing:
sudo chmod u-rwx /etc/hosts
sudo chmod u-rwx /etc/resolv.conf
Then, log into your account again. In doing this to users one by one you can block them from accessing the Internet at all.