E-mail users selected documents

What I've got to do is allow users to check which documents they'd like to have sent to them.

I need a cron script on how to do this in:

Studio 8 w/ PHP 5

mySQL 4.1

My backend schema is as follows with the table name and the proposed columns:

Parent table (PTUnique ID, e-mail address)

Join Table (PK of JTUnique ID, FK of PTUniqueID, FK of DTUniqueID)

Document Table (PK of DTUniqueID, document contents)

I'm going to keep working at this, but any ideas and suggestions are welcome.  When I get it done, I'll re-post here.

Thanks in advance