How to display the web page icon in the browser?

That icon called "favicon" You can simply generate it by online tools like these: http://tools.dynamicdrive.com/favicon/ http://www.favicon.cc/ All you need to upload the logo or image you want to use as icon and generate it there, it will not take a minute.

place a faveicon in the root directory of your website

Use Favicons :) http://en.wikipedia.org/wiki/Favicon

yes rename your logo icon to favicon.ico.
and also you can make a different icon for each directory.
you may also write this definition tags inside element:

Using Favicons