Though, Drupal 7 is in the beta release now..
Drupal6 is so far the most stable version.
I won't blabber about drupal i.e it is a CMS and all that stuff.. you already are aware of.
So let's get going..
A few basic things that always matters when it comes to customization.
1. theming.
- it includes css/js/tpl
2. form variables like $form and other stuff..
- you should also know how to set a template for a particular form or node type.
Nothing to worry.. I will cover these all in the next post.