Need to add a condition between two fields in a view
This can be accomplished through the Form API.  However, if you are a PHP novice, you would probably be better off using the Conditional Fields module.  Although this is still in dev (no official release) for Drupal 7, it does work.  (If you have security-related requirements, you should use Form API instead though.)

Basically, the module provides you with a UI for adding conditions to fields.  The example you give is the same given on the module's page, so this is one solution to your problem.