There are a lot of scripts that you can customize for your application without knowing anything about PHP, but I really think this is one where you'd really be better off learning PHP before you tried to modify an existing bread crumb script.
Harry Fuecks has an excellent discussion on how to maintain this kind of script in Volume 1 of his PHP Anthology book. In order for you to understand that though, it will be necessary for you to first read through Chapter 2 of the book, where he discusses object oriented PHP.
This is one of those situations where you asked what time it is and you're told how to build the clock first. However, I think it's a foundation that will serve you well if you're going to code in PHP.