Hi,
Zend uses the standard mvc design pattern, so if you haven't read up on this, then I suggest you do some serious researching
. At the moment zf doesn't restrict you to a certain structure, but does give recommendations.
If you haven't read up on these:
Zend Framework
Zend Framework Tutorial — a/r/t by php|architect
PHP Coding Standard (draft) - Zend Framework Development - Zend Framework Wiki <-- standards are great... make sure do have one