Re: blocking any site..
If you are using Internet Explorer,
Go to Tools–>Internet Options–> go to “security” tab–>highlight “Restricted Sites” → now add the website u wish to block e.g. http://www.yahoo.com
– now click add and then OK – Then OK
Alternate way
Open the following file in Notepad
C:\windows\system32\drivers\etc\hosts
and add a line to it… e.g.
# Copyright (c) 1993-1999 Microsoft Corp.
#
# This is a sample HOSTS file used by Microsoft TCP/IP for Windows.
#
# This file contains the mappings of IP addresses to host names. Each
# entry should be kept on an individual line. The IP address should
# be placed in the first column followed by the corresponding host name.
# The IP address and the host name should be separated by at least one
# space.
#
# Additionally, comments (such as these) may be inserted on individual
# lines or following the machine name denoted by a '#' symbol.
#
# For example:
#
# 102.54.94.97 rhino.acme.com # source server
# 38.25.63.10 x.acme.com # x client host
127.0.0.1 localhost
**127.0.0.1 ****www.yahoo.com**
save the file that u just edited – (not save as)