when the user logs in using Security Assist, the user ID is stored in a session variable. You can create a recordset to query the users table using the Session variable to return the users information.
the link to the reservation page should contain an ID variable in the URL to the box the being reserver, for example:
create another recordset that uses the id URL variable to filter the books table to return the selected book.
these 2 recordsets can be used to pre populate the form fields.
Where you say that you are new to PHP , MySQL and Dreamweaver, i recommend that you purchase or borrow some books from the public library on the topic. The Foundation PHP Series by David Powers is a very good resource for getting started with PHP, MySQL and Dreamweaver.
The purpose of this forum is to offer support for WebAssist Products. I don't mind helping with the occasional Dreamweaver specific question, but it is not the purpose of this forum to teach you the specifics of using PHP, MySQL and Dreamweaver for dynamic development.