This tutorial is only for users who are using windows XP

First open "C" drive or any drive in which windows is installed...

Then open "windows" folder...

Then open "system32".....

Then open "drivers" directory....

Then open "etc".....

The address will be "C:\WINDOWS\system32\drivers\etc"

Then look for a file named "hosts" the file has no extension.....

open it in the notepad.....

alternative method to open the file is given

open run by pressing ctrl + R

Then copy "C:\WINDOWS\system32\drivers\etc\hosts" and paste it into the run...

Press enter

select notepad to open it....

the file will appear as

# 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

Now add the websites u want to block at the end....

The format iz....

127.0.0.2 1st website to block
127.0.0.3 2nd website to block
127.0.0.4 3rd website to block
.
.
.
.
so on

for example if u want to block www.Microsoft.com and www.internetdownloadmanager.com then edited hosts file will appear as

# 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
127.0.0.2 www.Microsoft.com 
127.0.0.3 www.internetdownloadmanager.com

Then save the hosts file....

To check it open ur default browser and try to open www.Microsoft.com orwww.internetdownloadmanager.com u will see the websites connot be accessed and an error will appear....

[NOTe: Remember 127.0.0.x is a loopback network connection. If you telnet, ftp, etc...
to it you are connected to your own machine.]