Views PHP references
There exists good documentation in Project Page of Views PHP module and Documentation under Read Documentation link in project page..


How to Use Views PHP in views filter
How to Use Views PHP as Views Output Field..


Some existing answers and tutorials which can explain better you can find below..

How can I insert PHP code in Views?

http://eureka.ykyuen.info/2012/03/10/drupal-7-add-php-field-to-view/