Making a quick alteration to your .htaccess file can be used to lock out areas of your website. It will protect any folder you select as well as and everything below it.
If you wish to protect your entire website, simply setup htaccess in your public_html directory (the root of your website). However, if you only wish to protect certain directories, you will need to set this up separately.
For updated information on how to password-protect your website using .htaccess, simply do a Google search for "how do I password protect my website using .htaccess", and you'll get a good answer.
Example:
http://webdesign.about.com/od/security/a/password_protec.htm
NOTE: You will also need to know your Absolute path -- which is /home/yourusername/public_html/ -- in order to complete the process.
