Tulasi,
In the Apache config file, httpd.conf, you will need to add a couple of directives to the top of the drectory structure that you want to protect.
An example section looks like this:
<Directory "C:/webserver/securedirectory/">
Options Indexes MultiViews
AllowOverride None
~ Next 4 line needs to be added.
AuthType Basic
AuthName "My secure directory"
AuthUserFile "c:/psswds/httpd.pass"
Require valid-user
~ End of the 4 lines
Order allow,deny
Allow from all
</Directory>
Hope this helps
Cheers
Justin