Hi Kaushik,
If you want to install joomla/drupal fallow the steps given below:
-> download joomla/drupal
-> unzip joomla into your wamp's www folder (eg C:\wamp\www\joomla)
-> start wamp
-> open a browser window and go to http://localhost/joomla
-> follow the on screen prompts to install joomla
If you want to create php files to run out side joomla/drupal, you can create a php file in your root folder(i.e., www) and run the file as http://localhost/yourfile
Apr 8, 2010